Merge branch 'main' into feature/github-ci

* build(deps-dev): bump express in /lect-player-web/src/main/frontend (#888)

Bumps [express](https://github.com/expressjs/express) from 4.18.2 to 4.19.2.
- [Release notes](https://github.com/expressjs/express/releases)
- [Changelog](https://github.com/expressjs/express/blob/master/History.md)
- [Commits](https://github.com/expressjs/express/compare/4.18.2...4.19.2)

---
updated-dependencies:
- dependency-name: express
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

* build(deps-dev): bump webpack-dev-middleware (#887)

Bumps [webpack-dev-middleware](https://github.com/webpack/webpack-dev-middleware) from 5.3.3 to 5.3.4.
- [Release notes](https://github.com/webpack/webpack-dev-middleware/releases)
- [Changelog](https://github.com/webpack/webpack-dev-middleware/blob/v5.3.4/CHANGELOG.md)
- [Commits](https://github.com/webpack/webpack-dev-middleware/compare/v5.3.3...v5.3.4)

---
updated-dependencies:
- dependency-name: webpack-dev-middleware
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

* build(deps-dev): bump follow-redirects (#886)

Bumps [follow-redirects](https://github.com/follow-redirects/follow-redirects) from 1.15.2 to 1.15.6.
- [Release notes](https://github.com/follow-redirects/follow-redirects/releases)
- [Commits](https://github.com/follow-redirects/follow-redirects/compare/v1.15.2...v1.15.6)

---
updated-dependencies:
- dependency-name: follow-redirects
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

* build(deps): bump org.apache.tomcat.embed:tomcat-embed-websocket (#895)

Bumps org.apache.tomcat.embed:tomcat-embed-websocket from 10.1.10 to 10.1.19.

---
updated-dependencies:
- dependency-name: org.apache.tomcat.embed:tomcat-embed-websocket
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

lect-core/src/main/java/org/lecturestudio/core/model/Document.java

@@ -28,7 +28,6 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.Objects;
 import java.util.UUID;
-import java.util.stream.Stream;
 
 import org.lecturestudio.core.geometry.Dimension2D;
 import org.lecturestudio.core.geometry.Rectangle2D;
@@ -758,8 +757,8 @@ public class Document {
 		pages.clear();
 
 		int pageCount = pdfDocument.getPageCount();
-		String[] prevSplitPageText = new String[2];
-		String[] splitPageText;
+
+		List<String> lastPageTextLines = List.of();
 
 		for (int number = 0; number < pageCount; number++) {
 			Page page = new Page(this, number);
@@ -772,26 +771,24 @@ public class Document {
 				}
 			}
 
-			splitPageText = page.getPageText().split("\n");
+			List<String> pageTextLines = pdfDocument.getPageTextLines(number, 2);
 
-			if (splitPageText.length >= 2 && prevSplitPageText.length >= 2 &&
-					Stream.of(prevSplitPageText[0], prevSplitPageText[1], splitPageText[0], splitPageText[1])
-							.allMatch(Objects::nonNull)) {
-				if (prevSplitPageText[0].equals(splitPageText[0]) && prevSplitPageText[1].equals(splitPageText[1])) {
-					page.setOverlay(true);
+			List<String> finalLastPageTextLines = lastPageTextLines;
+			List<String> differences = pageTextLines.stream()
+					.filter(element -> !finalLastPageTextLines.contains(element)).toList();
 
-					if (number > 0) {
-						Page prevPage = pages.get(number - 1);
-						prevPage.setOverlay(true);
-					}
-				}
-				else {
-					prevSplitPageText = splitPageText;
+			// The pages have equal content, thus mark them as overlay pages.
+			if (differences.isEmpty()) {
+				page.setOverlay(true);
+
+				if (number > 0) {
+					Page prevPage = pages.get(number - 1);
+					prevPage.setOverlay(true);
 				}
 			}
-			else {
-				prevSplitPageText = splitPageText;
-			}
+
+			lastPageTextLines = pageTextLines;
+
 			pages.add(page);
 		}
 

lect-core/src/main/java/org/lecturestudio/core/pdf/DocumentAdapter.java

@@ -130,6 +130,16 @@ public interface DocumentAdapter {
 	 */
 	String getPageText(int pageNumber) throws IOException;
 
+	/**
+	 * Get the text of the page as a list where each list entry represents a text line in the page.
+	 *
+	 * @param pageNumber The page number.
+	 * @param maxLines   The maximum number of lines to retrieve.
+	 *
+	 * @return the text of the page as a list of text lines in the page.
+	 */
+	List<String> getPageTextLines(int pageNumber, int maxLines);
+
 	/**
 	 * Get the word bounds of the page that has the specified page number.
 	 *

lect-core/src/main/java/org/lecturestudio/core/pdf/DocumentPlatformQueue.java

@@ -0,0 +1,25 @@
+/*
+ * Copyright (C) 2020 TU Darmstadt, Department of Computer Science,
+ * Embedded Systems and Applications Group.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package org.lecturestudio.core.pdf;
+
+public interface DocumentPlatformQueue {
+
+    void runInPlatformQueue(Runnable runnable);
+
+}

lect-core/src/main/java/org/lecturestudio/core/pdf/DocumentWorker.java

@@ -0,0 +1,83 @@
+/*
+ * Copyright (C) 2020 TU Darmstadt, Department of Computer Science,
+ * Embedded Systems and Applications Group.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package org.lecturestudio.core.pdf;
+
+import java.util.concurrent.LinkedBlockingQueue;
+
+public class DocumentWorker {
+
+    private final DocumentPlatformQueue eventQueue;
+
+    protected LinkedBlockingQueue<DocumentWorkerTask> queue;
+
+    protected boolean alive;
+
+    protected Thread thread;
+
+
+    public DocumentWorker(DocumentPlatformQueue eventQueue) {
+        this.eventQueue = eventQueue;
+
+        queue = new LinkedBlockingQueue<>();
+        thread = new Thread(this::run);
+    }
+
+    public void start() {
+        alive = true;
+
+        thread.start();
+    }
+
+    public void stop() {
+        alive = false;
+
+        thread.interrupt();
+    }
+
+    public void add(DocumentWorkerTask task) {
+        try {
+            queue.put(task);
+        }
+        catch (InterruptedException x) {
+            // Ignore
+        }
+    }
+
+    public void run() {
+        while (alive) {
+            final DocumentWorkerTask task;
+
+            try {
+                task = queue.take();
+            }
+            catch (InterruptedException x) {
+                break;
+            }
+
+            try {
+                task.runInBackground();
+
+                eventQueue.runInPlatformQueue(task);
+            }
+            catch (final Throwable t) {
+                eventQueue.runInPlatformQueue(() -> task.exception(t));
+            }
+        }
+    }
+}

lect-core/src/main/java/org/lecturestudio/core/pdf/DocumentWorkerTask.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2020 TU Darmstadt, Department of Computer Science,
+ * Embedded Systems and Applications Group.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package org.lecturestudio.core.pdf;
+
+public abstract class DocumentWorkerTask implements Runnable {
+
+    /**
+     * This method will be executed on the background thread.
+     */
+    public void runInBackground() {
+    }
+
+    /**
+     * This method will be executed on the UI thread if work() did not throw any exception.
+     */
+    public void run() {
+    }
+
+    /**
+     * This method will be executed on the UI thread if work() throws an exception.
+     *
+     * @param t The throwable containing the error.
+     */
+    public void exception(final Throwable t) {
+    }
+
+}

lect-core/src/main/java/org/lecturestudio/core/pdf/PdfDocument.java

@@ -317,6 +317,18 @@ public class PdfDocument {
 		return muPDFDocument.getPageText(pageNumber);
 	}
 
+	/**
+	 * Get the text of the page as a list where each list entry represents a text line in the page.
+	 *
+	 * @param pageNumber The page number.
+	 * @param maxLines   The maximum number of lines to retrieve.
+	 *
+	 * @return the text of the page as a list of text lines in the page.
+	 */
+	public List<String> getPageTextLines(int pageNumber, int maxLines) {
+		return muPDFDocument.getPageTextLines(pageNumber, maxLines);
+	}
+
 	/**
 	 * Get the word bounds of the page that has the specified page number.
 	 *

lect-core/src/main/java/org/lecturestudio/core/pdf/mupdf/MuPDFDocument.java

@@ -41,14 +41,9 @@ import java.io.IOException;
 import java.io.OutputStream;
 import java.lang.reflect.Constructor;
 import java.net.URI;
-import java.util.AbstractMap;
-import java.util.ArrayList;
-import java.util.HashMap;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Map;
-import java.util.Set;
+import java.util.*;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.stream.Collectors;
 
 import org.lecturestudio.core.geometry.Rectangle2D;
 import org.lecturestudio.core.io.BitConverter;
@@ -201,7 +196,6 @@ public class MuPDFDocument implements DocumentAdapter {
 			Page page = getPage(pageNumber);
 
 			SimpleTextWalker textWalker = new SimpleTextWalker(page.getBounds());
-
 			StructuredText structuredText = displayList.toStructuredText();
 			structuredText.walk(textWalker);
 
@@ -496,6 +490,62 @@ public class MuPDFDocument implements DocumentAdapter {
 		}
 	}
 
+	@Override
+	public List<String> getPageTextLines(int pageNumber, int maxLines) {
+		synchronized (mutex) {
+			List<String> lines = new ArrayList<>();
+			DisplayList displayList = getDisplayList(pageNumber);
+			StructuredText structuredText = displayList.toStructuredText();
+
+			// Sort page text blocks, so that the page text is chronologically ordered (top-down).
+			var sorted = Arrays.stream(structuredText.getBlocks())
+					.sorted((o1, o2) -> o1.bbox.y0 < o2.bbox.y0 ? -1 : 1)
+					.toList();
+
+			// Last text block y-position.
+			double lastY0 = Double.MAX_VALUE;
+			double lastY1 = Double.MAX_VALUE;
+
+			// Read text lines from each block.
+			for (var block : sorted) {
+				// Check if the blocks intersect each other.
+				boolean intersects = (block.bbox.y0 >= lastY0 && block.bbox.y0 <= lastY1)
+						|| (block.bbox.y1 >= lastY0 && block.bbox.y1 <= lastY1);
+
+				if (block.lines.length > 0) {
+					StructuredText.TextLine textLine = block.lines[0];
+
+					if (textLine.chars.length > 0) {
+						// Convert individual chars into lines of strings.
+						var text = Arrays.stream(textLine.chars)
+								.map(textChar -> Character.toString(textChar.c))
+								.collect(Collectors.joining(""));
+
+						// If the blocks intersect, merge the text into a single line.
+						if (intersects) {
+							// Get last line text.
+							int index = lines.size() - 1;
+							String lastLine = lines.get(index) + text;
+							lines.set(index, lastLine);
+						}
+						else {
+							lines.add(text);
+						}
+
+						if (lines.size() >= maxLines) {
+							break;
+						}
+					}
+				}
+
+				lastY0 = block.bbox.y0;
+				lastY1 = block.bbox.y1;
+			}
+
+			return lines;
+		}
+	}
+
 	/**
 	 * Get the display list of the {@link PageEntry} that is mapped to the specified page number.
 	 *

lect-core/src/main/java/org/lecturestudio/core/pdf/pdfbox/PDFBoxDocument.java

@@ -605,6 +605,11 @@ public class PDFBoxDocument implements DocumentAdapter {
 		return shapes;
 	}
 
+	@Override
+	public List<String> getPageTextLines(int pageNumber, int maxLines) {
+		return List.of();
+	}
+
 	private void loadOutline(PDDocumentCatalog catalog, PDOutlineItem item,
 			DocumentOutlineItem outline) {
 		if (isNull(item)) {

lect-core/src/main/java/org/lecturestudio/core/service/DocumentService.java

@@ -125,7 +125,7 @@ public class DocumentService {
 		final File file = new File(nonNull(templatePath) ? templatePath : "");
 
 		return CompletableFuture.supplyAsync(() -> {
-			// Search for a opened whiteboard.
+			// Search for an opened whiteboard.
 			Document whiteboard = documents.getFirstWhiteboard();
 
 			// If there isn't any whiteboard, then create one.

lect-core/src/main/resources/i18n/core_de_DE.properties

@@ -22,6 +22,9 @@ button.download = Herunterladen
 button.update = Aktualisieren
 button.record = Aufzeichnen
 
+label.reply = antwortet
+label.edited = Bearbeitet
+
 file.description.pdf = PDF-Folien
 file.description.recording = Vorlesungsaufzeichnung
 file.description.wav = Wave Sound

lect-core/src/main/resources/i18n/core_en_US.properties

@@ -22,6 +22,9 @@ button.download = Download
 button.update = Update
 button.record = Record
 
+label.reply = replies
+label.edited = Edited
+
 file.description.pdf = PDF Slides
 file.description.recording = Lecture Recording
 file.description.wav = Wave Sound

lect-player-web/src/main/frontend/package-lock.json

@@ -2129,43 +2129,6 @@
 			"integrity": "sha512-jDctJ/IVQbZoJykoeHbhXpOlNBqGNcwXJKJog42E5HDPUwQTSdjCHdihjj0DlnheQ7blbT6dHOafNAiS8ooQKA==",
 			"dev": true
 		},
-		"body-parser": {
-			"version": "1.20.1",
-			"resolved": "https://registry.npmjs.org/body-parser/-/body-parser-1.20.1.tgz",
-			"integrity": "sha512-jWi7abTbYwajOytWCQc37VulmWiRae5RyTpaCyDcS5/lMdtwSz5lOpDE67srw/HYe35f1z3fDQw+3txg7gNtWw==",
-			"dev": true,
-			"requires": {
-				"bytes": "3.1.2",
-				"content-type": "~1.0.4",
-				"debug": "2.6.9",
-				"depd": "2.0.0",
-				"destroy": "1.2.0",
-				"http-errors": "2.0.0",
-				"iconv-lite": "0.4.24",
-				"on-finished": "2.4.1",
-				"qs": "6.11.0",
-				"raw-body": "2.5.1",
-				"type-is": "~1.6.18",
-				"unpipe": "1.0.0"
-			},
-			"dependencies": {
-				"debug": {
-					"version": "2.6.9",
-					"resolved": "https://registry.npmjs.org/debug/-/debug-2.6.9.tgz",
-					"integrity": "sha512-bC7ElrdJaJnPbAP+1EotYvqZsb3ecl5wi6Bfi6BJTUcNowp6cvspg0jXznRTKDjm/E7AdgFBVeAPVMNcKGsHMA==",
-					"dev": true,
-					"requires": {
-						"ms": "2.0.0"
-					}
-				},
-				"ms": {
-					"version": "2.0.0",
-					"resolved": "https://registry.npmjs.org/ms/-/ms-2.0.0.tgz",
-					"integrity": "sha512-Tpp60P6IUJDTuOq/5Z8cdskzJujfwqfOTkrwIwj7IRISpnkJnT6SyJ4PCPnGMoFjC9ddhal5KVIYtAt97ix05A==",
-					"dev": true
-				}
-			}
-		},
 		"bonjour-service": {
 			"version": "1.1.0",
 			"resolved": "https://registry.npmjs.org/bonjour-service/-/bonjour-service-1.1.0.tgz",
@@ -2595,12 +2558,6 @@
 			"integrity": "sha512-ASFBup0Mz1uyiIjANan1jzLQami9z1PoYSZCiiYW2FczPbenXc45FZdBZLzOT+r6+iciuEModtmCti+hjaAk0A==",
 			"dev": true
 		},
-		"cookie": {
-			"version": "0.5.0",
-			"resolved": "https://registry.npmjs.org/cookie/-/cookie-0.5.0.tgz",
-			"integrity": "sha512-YZ3GUyn/o8gfKJlnlX7g7xq4gyO6OSuhGPKaaGssGB2qgDUS0gPgtTvoyZLTt9Ab6dC4hfc9dV5arkvc/OCmrw==",
-			"dev": true
-		},
 		"cookie-signature": {
 			"version": "1.0.6",
 			"resolved": "https://registry.npmjs.org/cookie-signature/-/cookie-signature-1.0.6.tgz",
@@ -3161,17 +3118,17 @@
 			}
 		},
 		"express": {
-			"version": "4.18.2",
-			"resolved": "https://registry.npmjs.org/express/-/express-4.18.2.tgz",
-			"integrity": "sha512-5/PsL6iGPdfQ/lKM1UuielYgv3BUoJfz1aUwU9vHZ+J7gyvwdQXFEBIEIaxeGf0GIcreATNyBExtalisDbuMqQ==",
+			"version": "4.19.2",
+			"resolved": "https://registry.npmjs.org/express/-/express-4.19.2.tgz",
+			"integrity": "sha512-5T6nhjsT+EOMzuck8JjBHARTHfMht0POzlA60WV2pMD3gyXw2LZnZ+ueGdNxG+0calOJcWKbpFcuzLZ91YWq9Q==",
 			"dev": true,
 			"requires": {
 				"accepts": "~1.3.8",
 				"array-flatten": "1.1.1",
-				"body-parser": "1.20.1",
+				"body-parser": "1.20.2",
 				"content-disposition": "0.5.4",
 				"content-type": "~1.0.4",
-				"cookie": "0.5.0",
+				"cookie": "0.6.0",
 				"cookie-signature": "1.0.6",
 				"debug": "2.6.9",
 				"depd": "2.0.0",
@@ -3205,6 +3162,32 @@
 					"integrity": "sha512-PCVAQswWemu6UdxsDFFX/+gVeYqKAod3D3UVm91jHwynguOwAvYPhx8nNlM++NqRcK6CxxpUafjmhIdKiHibqg==",
 					"dev": true
 				},
+				"body-parser": {
+					"version": "1.20.2",
+					"resolved": "https://registry.npmjs.org/body-parser/-/body-parser-1.20.2.tgz",
+					"integrity": "sha512-ml9pReCu3M61kGlqoTm2umSXTlRTuGTx0bfYj+uIUKKYycG5NtSbeetV3faSU6R7ajOPw0g/J1PvK4qNy7s5bA==",
+					"dev": true,
+					"requires": {
+						"bytes": "3.1.2",
+						"content-type": "~1.0.5",
+						"debug": "2.6.9",
+						"depd": "2.0.0",
+						"destroy": "1.2.0",
+						"http-errors": "2.0.0",
+						"iconv-lite": "0.4.24",
+						"on-finished": "2.4.1",
+						"qs": "6.11.0",
+						"raw-body": "2.5.2",
+						"type-is": "~1.6.18",
+						"unpipe": "1.0.0"
+					}
+				},
+				"cookie": {
+					"version": "0.6.0",
+					"resolved": "https://registry.npmjs.org/cookie/-/cookie-0.6.0.tgz",
+					"integrity": "sha512-U71cyTamuh1CRNCfpGY6to28lxvNwPG4Guz/EVjgf3Jmzv0vlDp1atT9eS5dDjMYHucpHbWns6Lwf3BKz6svdw==",
+					"dev": true
+				},
 				"debug": {
 					"version": "2.6.9",
 					"resolved": "https://registry.npmjs.org/debug/-/debug-2.6.9.tgz",
@@ -3219,6 +3202,18 @@
 					"resolved": "https://registry.npmjs.org/ms/-/ms-2.0.0.tgz",
 					"integrity": "sha512-Tpp60P6IUJDTuOq/5Z8cdskzJujfwqfOTkrwIwj7IRISpnkJnT6SyJ4PCPnGMoFjC9ddhal5KVIYtAt97ix05A==",
 					"dev": true
+				},
+				"raw-body": {
+					"version": "2.5.2",
+					"resolved": "https://registry.npmjs.org/raw-body/-/raw-body-2.5.2.tgz",
+					"integrity": "sha512-8zGqypfENjCIqGhgXToC8aB2r7YrBX+AQAfIPs/Mlk+BtPTztOvTS01NRW/3Eh60J+a48lt8qsCzirQ6loCVfA==",
+					"dev": true,
+					"requires": {
+						"bytes": "3.1.2",
+						"http-errors": "2.0.0",
+						"iconv-lite": "0.4.24",
+						"unpipe": "1.0.0"
+					}
 				}
 			}
 		},
@@ -3345,9 +3340,9 @@
 			}
 		},
 		"follow-redirects": {
-			"version": "1.15.2",
-			"resolved": "https://registry.npmjs.org/follow-redirects/-/follow-redirects-1.15.2.tgz",
-			"integrity": "sha512-VQLG33o04KaQ8uYi2tVNbdrWp1QWxNNea+nmIB4EVM28v0hmP17z7aG1+wAkNzVq4KeXTq3221ye5qTJP91JwA==",
+			"version": "1.15.6",
+			"resolved": "https://registry.npmjs.org/follow-redirects/-/follow-redirects-1.15.6.tgz",
+			"integrity": "sha512-wWN62YITEaOpSK584EZXJafH1AGpO8RVgElfkuXbTOrPX4fIfOyEpW/CsiNd8JdYrAoOvafRTOEnvsO++qCqFA==",
 			"dev": true
 		},
 		"for-each": {
@@ -4993,18 +4988,6 @@
 			"integrity": "sha512-Hrgsx+orqoygnmhFbKaHE6c296J+HTAQXoxEF6gNupROmmGJRoyzfG3ccAveqCBrwr/2yxQ5BVd/GTl5agOwSg==",
 			"dev": true
 		},
-		"raw-body": {
-			"version": "2.5.1",
-			"resolved": "https://registry.npmjs.org/raw-body/-/raw-body-2.5.1.tgz",
-			"integrity": "sha512-qqJBtEyVgS0ZmPGdCFPWJ3FreoqvG4MVQln/kCgF7Olq95IbOp0/BWyMwbdtn4VTvkM8Y7khCQ2Xgk/tcrCXig==",
-			"dev": true,
-			"requires": {
-				"bytes": "3.1.2",
-				"http-errors": "2.0.0",
-				"iconv-lite": "0.4.24",
-				"unpipe": "1.0.0"
-			}
-		},
 		"readable-stream": {
 			"version": "3.6.0",
 			"resolved": "https://registry.npmjs.org/readable-stream/-/readable-stream-3.6.0.tgz",
@@ -6336,9 +6319,9 @@
 			}
 		},
 		"webpack-dev-middleware": {
-			"version": "5.3.3",
-			"resolved": "https://registry.npmjs.org/webpack-dev-middleware/-/webpack-dev-middleware-5.3.3.tgz",
-			"integrity": "sha512-hj5CYrY0bZLB+eTO+x/j67Pkrquiy7kWepMHmUMoPsmcUaeEnQJqFzHJOyxgWlq746/wUuA64p9ta34Kyb01pA==",
+			"version": "5.3.4",
+			"resolved": "https://registry.npmjs.org/webpack-dev-middleware/-/webpack-dev-middleware-5.3.4.tgz",
+			"integrity": "sha512-BVdTqhhs+0IfoeAf7EoH5WE+exCmqGerHfDM0IL096Px60Tq2Mn9MAbnaGUe6HiMa41KMCYF19gyzZmBcq/o4Q==",
 			"dev": true,
 			"requires": {
 				"colorette": "^2.0.10",
@@ -6376,15 +6359,15 @@
 					"dev": true
 				},
 				"schema-utils": {
-					"version": "4.0.0",
-					"resolved": "https://registry.npmjs.org/schema-utils/-/schema-utils-4.0.0.tgz",
-					"integrity": "sha512-1edyXKgh6XnJsJSQ8mKWXnN/BVaIbFMLpouRUrXgVq7WYne5kw3MW7UPhO44uRXQSIpTSXoJbmrR2X0w9kUTyg==",
+					"version": "4.2.0",
+					"resolved": "https://registry.npmjs.org/schema-utils/-/schema-utils-4.2.0.tgz",
+					"integrity": "sha512-L0jRsrPpjdckP3oPug3/VxNKt2trR8TcabrM6FOAAlvC/9Phcmm+cuAgTlxBqdBR1WJx7Naj9WHw+aOmheSVbw==",
 					"dev": true,
 					"requires": {
 						"@types/json-schema": "^7.0.9",
-						"ajv": "^8.8.0",
+						"ajv": "^8.9.0",
 						"ajv-formats": "^2.1.1",
-						"ajv-keywords": "^5.0.0"
+						"ajv-keywords": "^5.1.0"
 					}
 				}
 			}

lect-presenter-api/src/main/java/org/lecturestudio/presenter/api/context/PresenterContext.java

@@ -21,6 +21,7 @@ package org.lecturestudio.presenter.api.context;
 import static java.util.Objects.isNull;
 
 import java.io.File;
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Set;
 
@@ -68,6 +69,8 @@ public class PresenterContext extends ApplicationContext {
 
 	private final ObservableList<MessengerMessage> messengerMessages = new ObservableArrayList<>();
 
+	private final List<MessengerMessage> allReceivedMessengerMessages = new ArrayList<>();
+
 	private final IntegerProperty messageCount = new IntegerProperty();
 
 	private final ObservableList<SpeechRequestMessage> speechRequests = new ObservableArrayList<>();
@@ -187,6 +190,10 @@ public class PresenterContext extends ApplicationContext {
 		return messengerMessages;
 	}
 
+	public List<MessengerMessage> getAllReceivedMessengerMessages() {
+		return allReceivedMessengerMessages;
+	}
+
 	public List<SpeechRequestMessage> getSpeechRequests() {
 		return speechRequests;
 	}

lect-presenter-api/src/main/java/org/lecturestudio/presenter/api/event/ExternalMessagesViewEvent.java

@@ -1,6 +1,7 @@
 package org.lecturestudio.presenter.api.event;
 
 public class ExternalMessagesViewEvent extends ExternalViewEvent {
+
 	public ExternalMessagesViewEvent(boolean enabled) {
 		super(enabled);
 	}

lect-presenter-api/src/main/java/org/lecturestudio/presenter/api/presenter/CefStreamPresenter.java

@@ -120,10 +120,10 @@ public abstract class CefStreamPresenter<T extends View> extends Presenter<T> {
 
 		// Open the running course url.
 		StreamConfiguration streamConfig = ctx.getConfiguration().getStreamConfig();
-		long courseId = ctx.getCourse().getId();
+		String accessLink = ctx.getCourse().getDefaultAccessLink();
 		String serverName = streamConfig.getServerName();
 		String serverUrl = String.format("https://%s", serverName);
-		String courseApiUrl = String.format("%s/course/api/%d", serverUrl, courseId);
+		String courseApiUrl = String.format("%s/course/api/%s", serverUrl, accessLink);
 
 		browser = client.createBrowser(courseApiUrl, false, false);
 	}

lect-presenter-api/src/main/java/org/lecturestudio/presenter/api/presenter/MainPresenter.java

@@ -95,9 +95,11 @@ import org.lecturestudio.presenter.api.service.ScreenSourceService;
 import org.lecturestudio.presenter.api.service.StreamService;
 import org.lecturestudio.presenter.api.handler.shutdown.SaveDocumentsHandler;
 import org.lecturestudio.presenter.api.handler.shutdown.SaveRecordingHandler;
+import org.lecturestudio.presenter.api.service.WebService;
 import org.lecturestudio.presenter.api.util.ScreenDocumentCreator;
 import org.lecturestudio.presenter.api.view.MainView;
 import org.lecturestudio.web.api.exception.StreamMediaException;
+import org.lecturestudio.web.api.message.StopStreamEnvironmentMessage;
 
 public class MainPresenter extends org.lecturestudio.core.presenter.MainPresenter<MainView> implements ViewHandler {
 
@@ -131,6 +133,8 @@ public class MainPresenter extends org.lecturestudio.core.presenter.MainPresente
 
 	private final ScreenShareService screenShareService;
 
+	private final WebService webService;
+
 	private SlidesPresenter slidesPresenter;
 
 	/** The waiting notification. */
@@ -147,7 +151,8 @@ public class MainPresenter extends org.lecturestudio.core.presenter.MainPresente
 			BookmarkService bookmarkService,
 			RecordingService recordingService,
 			StreamService streamService,
-			ScreenShareService screenShareService) {
+			ScreenShareService screenShareService,
+			WebService webService) {
 		super(context, view);
 
 		this.audioSystemProvider = audioSystemProvider;
@@ -160,6 +165,7 @@ public class MainPresenter extends org.lecturestudio.core.presenter.MainPresente
 		this.streamService = streamService;
 		this.screenSourceService = new ScreenSourceService();
 		this.screenShareService = screenShareService;
+		this.webService = webService;
 		this.viewMap = new ObservableHashMap<>();
 		this.shortcutMap = new HashMap<>();
 		this.contexts = new ArrayList<>();
@@ -336,6 +342,7 @@ public class MainPresenter extends org.lecturestudio.core.presenter.MainPresente
 		if (state == ExecutableState.Stopped) {
 			PresenterContext presenterContext = (PresenterContext) context;
 			presenterContext.getMessengerMessages().clear();
+			presenterContext.getAllReceivedMessengerMessages().clear();
 
 //			destroyHandler(MessengerWindowPresenter.class);
 		}
@@ -455,6 +462,33 @@ public class MainPresenter extends org.lecturestudio.core.presenter.MainPresente
 		}
 	}
 
+	@Subscribe
+	public void onEvent(StopStreamEnvironmentMessage event) {
+		//This method tries to force the stop of all stream components (stream, messenger, quiz) even if they might be inactive from this side
+
+		final String initiator = String.format("%s %s", event.getFirstName(), event.getFamilyName());
+
+		try {
+			webService.stopQuiz();
+		}
+		catch (Exception exception) {
+			logException(exception, "Stop quiz failed");
+		}
+		try {
+			webService.stopMessenger();
+		}
+		catch (Exception exception) {
+			logException(exception, "Stop messenger failed");
+		}
+
+		((PresenterContext) context).setStreamStarted(false);
+
+		context.showNotification(NotificationType.WARNING,
+			"stream.environment.stopped.by.message.title",
+			"stream.environment.stopped.by.message",
+			initiator);
+	}
+
 	@Override
 	public void addShutdownHandler(ShutdownHandler handler) {
 		requireNonNull(handler, "ShutdownHandler must not be null.");

lect-presenter-api/src/main/java/org/lecturestudio/presenter/api/presenter/MessengerWindowPresenter.java

@@ -28,9 +28,11 @@ import org.lecturestudio.core.app.ApplicationContext;
 import org.lecturestudio.core.app.configuration.Configuration;
 import org.lecturestudio.core.presenter.Presenter;
 import org.lecturestudio.core.view.ViewLayer;
+import org.lecturestudio.presenter.api.context.PresenterContext;
 import org.lecturestudio.presenter.api.view.MessengerWindow;
 import org.lecturestudio.web.api.message.MessengerMessage;
 import org.lecturestudio.web.api.message.SpeechRequestMessage;
+import org.lecturestudio.web.api.message.util.MessageUtil;
 
 public class MessengerWindowPresenter extends Presenter<MessengerWindow> {
 
@@ -81,6 +83,26 @@ public class MessengerWindowPresenter extends Presenter<MessengerWindow> {
 		requireNonNull(message);
 
 		view.setMessengerMessage(message);
+
+		if(message.isDeleted()) {
+			view.removeMessengerMessage(message.getMessageId());
+			return;
+		}
+
+		if(message.isEdited()) {
+			view.setModifiedMessengerMessage(message);
+			return;
+		}
+
+		if(MessageUtil.isReply(message)) {
+			final MessengerMessage messageToReplyTo = MessageUtil.findMessageToReplyTo(
+					((PresenterContext) context).getAllReceivedMessengerMessages(),
+					message);
+			view.setMessengerMessageAsReply(message, messageToReplyTo);
+		}
+		else {
+			view.setMessengerMessage(message);
+		}
 	}
 
 	@Subscribe

lect-presenter-api/src/main/java/org/lecturestudio/presenter/api/presenter/SlidesPresenter.java

@@ -124,6 +124,7 @@ import org.lecturestudio.web.api.message.MessengerMessage;
 import org.lecturestudio.web.api.message.SpeechBaseMessage;
 import org.lecturestudio.web.api.message.SpeechCancelMessage;
 import org.lecturestudio.web.api.message.SpeechRequestMessage;
+import org.lecturestudio.web.api.message.util.MessageUtil;
 import org.lecturestudio.web.api.model.Message;
 import org.lecturestudio.web.api.model.ScreenSource;
 import org.lecturestudio.web.api.service.ServiceParameters;
@@ -166,6 +167,8 @@ public class SlidesPresenter extends Presenter<SlidesView> {
 
 	private final RecordingService recordingService;
 
+	private final UserPrivilegeService userPrivilegeService;
+
 	private StylusHandler stylusHandler;
 
 	private PageEditedListener pageEditedListener;
@@ -184,8 +187,6 @@ public class SlidesPresenter extends Presenter<SlidesView> {
 
 	private SelectionIdleTimer idleTimer;
 
-	private final UserPrivilegeService userPrivilegeService;
-
 
 	@Inject
 	SlidesPresenter(ApplicationContext context, SlidesView view,
@@ -197,10 +198,10 @@ public class SlidesPresenter extends Presenter<SlidesView> {
 					DocumentService documentService,
 					DocumentRecorder documentRecorder,
 					RecordingService recordingService,
+					UserPrivilegeService userPrivilegeService,
 					WebService webService,
 					WebServiceInfo webServiceInfo,
-					WebRtcStreamService streamService,
-					UserPrivilegeService userPrivilegeService) {
+					WebRtcStreamService streamService) {
 		super(context, view);
 
 		this.viewFactory = viewFactory;
@@ -211,6 +212,7 @@ public class SlidesPresenter extends Presenter<SlidesView> {
 		this.bookmarkService = bookmarkService;
 		this.documentService = documentService;
 		this.recordingService = recordingService;
+		this.userPrivilegeService = userPrivilegeService;
 		this.webService = webService;
 		this.webServiceInfo = webServiceInfo;
 		this.streamService = streamService;
@@ -219,7 +221,6 @@ public class SlidesPresenter extends Presenter<SlidesView> {
 		this.pageObjectRegistry = new PageObjectRegistry();
 		this.documentChangeListener = new DocumentChangeHandler();
 		this.screenViewContext = new ScreenPresentationViewContext();
-		this.userPrivilegeService = userPrivilegeService;
 	}
 
 	@Subscribe
@@ -356,9 +357,32 @@ public class SlidesPresenter extends Presenter<SlidesView> {
 		requireNonNull(message);
 
 		PresenterContext presenterContext = (PresenterContext) context;
-		presenterContext.getMessengerMessages().add(message);
 
-		view.setMessengerMessage(message);
+		if (message.isDeleted()) {
+			onDiscardMessage(message);
+			view.removeMessengerMessage(message.getMessageId());
+			return;
+		}
+
+		if (message.isEdited()) {
+			view.setModifiedMessengerMessage(message);
+			MessageUtil.updateOutdatedMessage(presenterContext.getMessengerMessages(), message);
+			MessageUtil.updateOutdatedMessage(presenterContext.getAllReceivedMessengerMessages(), message);
+			return;
+		}
+
+		presenterContext.getMessengerMessages().add(message);
+		presenterContext.getAllReceivedMessengerMessages().add(message);
+
+		if (MessageUtil.isReply(message)) {
+			final MessengerMessage messageToReplyTo = MessageUtil.findMessageToReplyTo(
+					((PresenterContext) context).getAllReceivedMessengerMessages(),
+					message);
+			view.setMessengerMessageAsReply(message, messageToReplyTo);
+		}
+		else {
+			view.setMessengerMessage(message);
+		}
 	}
 
 	@Subscribe
@@ -1467,7 +1491,9 @@ public class SlidesPresenter extends Presenter<SlidesView> {
 					return;
 				}
 
-				action.accept(config.isEnabled(), checkIfScreenInList(list, config.getScreen()));
+				checkScreenExists(config);
+
+				action.accept(config.isEnabled(), true);
 			}
 		});
 	}
@@ -1502,9 +1528,9 @@ public class SlidesPresenter extends Presenter<SlidesView> {
 	}
 
 	private void showExternalScreen(ExternalWindowConfiguration config, BiConsumer<Boolean, Boolean> action) {
-		final ObservableList<Screen> screens = presentationController.getScreens();
+		checkScreenExists(config);
 
-		action.accept(config.isEnabled(), checkIfScreenInList(screens, config.getScreen()));
+		action.accept(config.isEnabled(), true);
 	}
 
 	private void hideExternalScreens() {
@@ -1513,6 +1539,14 @@ public class SlidesPresenter extends Presenter<SlidesView> {
 		view.hideExternalSpeech();
 	}
 
+	private void checkScreenExists(ExternalWindowConfiguration config) {
+		final ObservableList<Screen> screens = presentationController.getScreens();
+
+		if (!checkIfScreenInList(screens, config.getScreen())) {
+			config.setScreen(null);
+		}
+	}
+
 	private void viewShowExternalMessages(boolean persistent) {
 		final ExternalWindowConfiguration config = getExternalMessagesConfig();
 
@@ -1520,6 +1554,8 @@ public class SlidesPresenter extends Presenter<SlidesView> {
 			config.setEnabled(true);
 		}
 
+		checkScreenExists(config);
+
 		view.showExternalMessages(config.getScreen(), config.getPosition(), config.getSize());
 	}
 
@@ -1540,6 +1576,8 @@ public class SlidesPresenter extends Presenter<SlidesView> {
 			config.setEnabled(true);
 		}
 
+		checkScreenExists(config);
+
 		view.showExternalParticipants(config.getScreen(), config.getPosition(), config.getSize());
 	}
 
@@ -1560,6 +1598,8 @@ public class SlidesPresenter extends Presenter<SlidesView> {
 			config.setEnabled(true);
 		}
 
+		checkScreenExists(config);
+
 		view.showExternalSlidePreview(config.getScreen(), config.getPosition(), config.getSize());
 	}
 
@@ -1580,6 +1620,8 @@ public class SlidesPresenter extends Presenter<SlidesView> {
 			config.setEnabled(true);
 		}
 
+		checkScreenExists(config);
+
 		view.showExternalSpeech(config.getScreen(), config.getPosition(), config.getSize());
 	}
 
@@ -1600,6 +1642,8 @@ public class SlidesPresenter extends Presenter<SlidesView> {
 			config.setEnabled(true);
 		}
 
+		checkScreenExists(config);
+
 		view.showExternalNotes(config.getScreen(), config.getPosition(), config.getSize());
 	}
 
@@ -1620,6 +1664,8 @@ public class SlidesPresenter extends Presenter<SlidesView> {
 			config.setEnabled(true);
 		}
 
+		checkScreenExists(config);
+
 		view.showExternalSlideNotes(config.getScreen(), config.getPosition(), config.getSize());
 	}
 
@@ -1637,7 +1683,7 @@ public class SlidesPresenter extends Presenter<SlidesView> {
 		if (screen == null) {
 			return true;
 		}
-		return screens.stream().anyMatch(scrn -> scrn.equals(screen));
+		return screens.stream().anyMatch(s -> s.equals(screen));
 	}
 
 	private void recordPage(Page page) {

lect-presenter-api/src/main/java/org/lecturestudio/presenter/api/presenter/ToolbarPresenter.java

@@ -310,7 +310,7 @@ public class ToolbarPresenter extends Presenter<ToolbarView> {
 			String template = config.getTemplateConfig()
 					.getWhiteboardTemplateConfig().getTemplatePath();
 
-			documentService.openWhiteboard(template).join();
+			documentService.openWhiteboard(template);
 		}
 		else {
 			documentService.selectDocument(documents.getLastNonWhiteboard());

lect-presenter-api/src/main/java/org/lecturestudio/presenter/api/service/WebService.java

@@ -38,6 +38,7 @@ import org.lecturestudio.presenter.api.event.MessengerStateEvent;
 import org.lecturestudio.presenter.api.event.QuizStateEvent;
 import org.lecturestudio.presenter.api.net.LocalBroadcaster;
 import org.lecturestudio.web.api.client.TokenProvider;
+import org.lecturestudio.web.api.message.StopStreamEnvironmentMessage;
 import org.lecturestudio.web.api.message.CoursePresenceMessage;
 import org.lecturestudio.web.api.message.MessageTransport;
 import org.lecturestudio.web.api.message.SpeechBaseMessage;
@@ -364,6 +365,9 @@ public class WebService extends ExecutableBase {
 			messageTransport.addListener(SpeechBaseMessage.class, message -> {
 				context.getEventBus().post(message);
 			});
+			messageTransport.addListener(StopStreamEnvironmentMessage.class, message -> {
+				context.getEventBus().post(message);
+			});
 		}
 	}
 

lect-presenter-api/src/main/java/org/lecturestudio/presenter/api/view/MessengerWindow.java

@@ -27,6 +27,12 @@ public interface MessengerWindow extends View {
 
 	void setMessengerMessage(MessengerMessage message);
 
+	void setMessengerMessageAsReply(MessengerMessage message, MessengerMessage messageToReplyTo);
+
+	void setModifiedMessengerMessage(MessengerMessage modifiedMessage);
+
+	void removeMessengerMessage(String messageId);
+
 	void setSpeechRequestMessage(SpeechRequestMessage message);
 
 	void setTextSize(double size);

lect-presenter-api/src/main/java/org/lecturestudio/presenter/api/view/SlidesView.java

@@ -102,6 +102,12 @@ public interface SlidesView extends View {
 
 	void setMessengerMessage(MessengerMessage message);
 
+	void removeMessengerMessage(String messageId);
+
+	void setMessengerMessageAsReply(MessengerMessage message, MessengerMessage messageToReplyTo);
+
+	void setModifiedMessengerMessage(MessengerMessage modifiedMessage);
+
 	void addSpeechRequest(SpeechBaseMessage message);
 
 	void removeSpeechRequest(SpeechBaseMessage message);

lect-presenter-api/src/main/resources/i18n/dict_de_DE.properties

@@ -1,5 +1,5 @@
-audio.device.connected = Audiogerät verbunden
-audio.device.disconnected = Audiogerät getrennt
+audio.device.connected = Audioger\u00e4t verbunden
+audio.device.disconnected = Audioger\u00e4t getrennt
 
 bookmark.assign.warning = Lesezeichen konnte nicht erstellt werden
 bookmark.delete.error = Lesezeichen konnte nicht gel\u00f6scht werden
@@ -16,7 +16,7 @@ document.save.lecture = Vorlesung
 error = Fehler
 generic.error = Bitte kontaktieren Sie Ihren Systemadministrator. Vollst\u00e4ndige Details finden Sie im Anwendungsprotokoll.
 
-please.wait = Einen Moment bitte...
+please.wait = Einen Moment bitte ...
 
 messenger.starting = Der Messenger wird gestartet
 messenger.start.error = Messenger konnte nicht gestartet werden
@@ -76,6 +76,7 @@ text.message = Nachricht
 text.message.time = Datum / Uhrzeit
 text.messages = Textnachrichten
 text.message.me = Ich
+text.message.me.dative = Mir
 text.message.privately = Privat
 text.message.recipient = {0} an {1}
 text.message.to.me = mich
@@ -144,4 +145,7 @@ shortcut.color.one = Farbe 1
 shortcut.color.two = Farbe 2
 shortcut.color.three = Farbe 3
 shortcut.color.four = Farbe 4
-shortcut.color.five = Farbe 5
+shortcut.color.five = Farbe 5
+
+stream.environment.stopped.by.message.title = Stream-Umgebung stoppen
+stream.environment.stopped.by.message = Stoppen der Stream-Umgebung bestehend aus Quiz, Messenger und Stream wurde initiiert. Initiator: {0}

lect-presenter-api/src/main/resources/i18n/dict_en_US.properties

@@ -16,7 +16,7 @@ document.save.lecture = Lecture
 error = Error
 generic.error = Please contact your system administrator. For complete details, see the application log.
 
-please.wait = One moment please...
+please.wait = One moment please ...
 
 messenger.starting = Starting Messenger
 messenger.start.error = Messenger could not be started
@@ -76,6 +76,7 @@ text.message = Message
 text.message.time = Date / Time
 text.messages = Text Messages
 text.message.me = Me
+text.message.dative = Me
 text.message.privately = Privately
 text.message.recipient = {0} to {1}
 text.message.to.me = me
@@ -144,4 +145,7 @@ shortcut.color.one = Color 1
 shortcut.color.two = Color 2
 shortcut.color.three = Color 3
 shortcut.color.four = Color 4
-shortcut.color.five = Color 5
+shortcut.color.five = Color 5
+
+stream.environment.stopped.by.message.title = Stream-environment stopped
+stream.environment.stopped.by.message = Stop of Stream-environment consisting of quiz, messenger and stream was initiated. Initiator: {0}

lect-presenter-api/src/test/java/org/lecturestudio/presenter/api/presenter/MainPresenterTest.java

@@ -65,7 +65,11 @@ import org.lecturestudio.presenter.api.context.PresenterContext;
 import org.lecturestudio.presenter.api.input.Shortcut;
 import org.lecturestudio.presenter.api.net.LocalBroadcaster;
 import org.lecturestudio.presenter.api.recording.FileLectureRecorder;
-import org.lecturestudio.presenter.api.service.*;
+import org.lecturestudio.presenter.api.service.BookmarkService;
+import org.lecturestudio.presenter.api.service.RecordingService;
+import org.lecturestudio.presenter.api.service.WebRtcStreamService;
+import org.lecturestudio.presenter.api.service.WebService;
+import org.lecturestudio.presenter.api.service.WebServiceInfo;
 import org.lecturestudio.presenter.api.view.MainView;
 import org.lecturestudio.presenter.api.view.QuitRecordingView;
 import org.lecturestudio.presenter.api.view.RestoreRecordingView;
@@ -196,7 +200,7 @@ class MainPresenterTest extends PresenterTest {
 			public <T> T getInstance(Class<T> cls) {
 				if (cls == SlidesPresenter.class) {
 					ToolController toolController = new ToolController(context, documentService);
-					return (T) new SlidesPresenter(context, createProxy(SlidesView.class), null, toolController, presentationController, null, bookmarkService, documentService, documentRecorder, recordingService, webService, webServiceInfo, streamService, null);
+					return (T) new SlidesPresenter(context, createProxy(SlidesView.class), null, toolController, presentationController, null, bookmarkService, documentService, documentRecorder, recordingService, null, webService, webServiceInfo, streamService);
 				}
 				else if (cls == SettingsPresenter.class) {
 					return (T) new SettingsPresenter(context, createProxy(SettingsView.class));
@@ -232,7 +236,7 @@ class MainPresenterTest extends PresenterTest {
 
 		MainPresenter presenter = new MainPresenter(context, view,
 				audioSystemProvider, presentationController, null, viewFactory,
-				documentService, bookmarkService, recordingService, null, null);
+				documentService, bookmarkService, recordingService, null, null, null);
 		presenter.initialize();
 		presenter.showView(testView, ViewLayer.Content);
 	}
@@ -270,7 +274,7 @@ class MainPresenterTest extends PresenterTest {
 
 		MainPresenter presenter = new MainPresenter(context, view,
 				audioSystemProvider, presentationController, null, viewFactory,
-				documentService, bookmarkService, recordingService, null, null);
+				documentService, bookmarkService, recordingService, null, null, null);
 		presenter.initialize();
 		presenter.display(new TestPresenter(context, new TestView()));
 
@@ -321,7 +325,7 @@ class MainPresenterTest extends PresenterTest {
 
 		MainPresenter presenter = new MainPresenter(context, view,
 				audioSystemProvider, presentationController, null, viewFactory,
-				documentService, bookmarkService, recordingService, null, null);
+				documentService, bookmarkService, recordingService, null, null, null);
 		presenter.initialize();
 		presenter.display(new TestPresenter(context, new TestView()));
 
@@ -367,7 +371,7 @@ class MainPresenterTest extends PresenterTest {
 
 		MainPresenter presenter = new MainPresenter(context, view,
 				audioSystemProvider, presentationController, null, viewFactory,
-				documentService, bookmarkService, recordingService, null, null);
+				documentService, bookmarkService, recordingService, null, null, null);
 		presenter.initialize();
 		presenter.display(testPresenter);
 		presenter.destroy(testPresenter);
@@ -414,7 +418,7 @@ class MainPresenterTest extends PresenterTest {
 
 		MainPresenter presenter = new MainPresenter(context, view,
 				audioSystemProvider, presentationController, null, viewFactory,
-				documentService, bookmarkService, recordingService, null, null);
+				documentService, bookmarkService, recordingService, null, null, null);
 		presenter.initialize();
 		presenter.display(testPresenter);
 		presenter.destroy(testPresenter);
@@ -436,7 +440,7 @@ class MainPresenterTest extends PresenterTest {
 
 		MainPresenter presenter = new MainPresenter(context, view,
 				audioSystemProvider, presentationController, null, viewFactory,
-				documentService, bookmarkService, recordingService, null, null);
+				documentService, bookmarkService, recordingService, null, null, null);
 		presenter.initialize();
 		presenter.setFullscreen(true);
 
@@ -474,7 +478,7 @@ class MainPresenterTest extends PresenterTest {
 
 		MainPresenter presenter = new MainPresenter(context, view,
 				audioSystemProvider, presentationController, null, viewFactory,
-				documentService, bookmarkService, recordingService, null, null);
+				documentService, bookmarkService, recordingService, null, null, null);
 		presenter.initialize();
 
 		view.shownAction.execute();
@@ -496,7 +500,7 @@ class MainPresenterTest extends PresenterTest {
 
 		MainPresenter presenter = new MainPresenter(context, view,
 				audioSystemProvider, presentationController, null, viewFactory,
-				documentService, bookmarkService, recordingService, null, null);
+				documentService, bookmarkService, recordingService, null, null, null);
 		presenter.initialize();
 		presenter.addShutdownHandler(new ShutdownHandler() {
 
@@ -538,7 +542,7 @@ class MainPresenterTest extends PresenterTest {
 
 		MainPresenter presenter = new MainPresenter(context, view,
 				audioSystemProvider, presentationController, null, viewFactory,
-				documentService, bookmarkService, recordingService, null, null);
+				documentService, bookmarkService, recordingService, null, null, null);
 		presenter.initialize();
 		presenter.display(new TestPresenter(context, new TestView()));
 
@@ -565,7 +569,7 @@ class MainPresenterTest extends PresenterTest {
 
 		MainPresenter presenter = new MainPresenter(context, view,
 				audioSystemProvider, presentationController, null, viewFactory,
-				documentService, bookmarkService, recordingService, null, null);
+				documentService, bookmarkService, recordingService, null, null, null);
 		presenter.initialize();
 
 		recordingService.start();
@@ -601,7 +605,7 @@ class MainPresenterTest extends PresenterTest {
 
 		MainPresenter presenter = new MainPresenter(context, view,
 				audioSystemProvider, presentationController, null, viewFactory,
-				documentService, bookmarkService, recordingService, null, null);
+				documentService, bookmarkService, recordingService, null, null, null);
 		presenter.initialize();
 
 		ToolController toolController = new ToolController(context, documentService);

lect-presenter-api/src/test/java/org/lecturestudio/presenter/api/presenter/MessengerWindowPresenterTest.java

@@ -106,6 +106,21 @@ class MessengerWindowPresenterTest extends PresenterTest {
 
 		}
 
+		@Override
+		public void setMessengerMessageAsReply(MessengerMessage message, MessengerMessage messageToReplyTo) {
+
+		}
+
+		@Override
+		public void setModifiedMessengerMessage(MessengerMessage modifiedMessage) {
+
+		}
+
+		@Override
+		public void removeMessengerMessage(String messageId) {
+
+		}
+
 		@Override
 		public void setSpeechRequestMessage(SpeechRequestMessage message) {
 

lect-presenter-swing/src/main/java/org/lecturestudio/presenter/swing/utils/ViewUtil.java

@@ -24,6 +24,7 @@ import org.lecturestudio.core.app.dictionary.Dictionary;
 import org.lecturestudio.swing.components.MessagePanel;
 import org.lecturestudio.swing.components.NotesPanel;
 import org.lecturestudio.web.api.message.UserMessage;
+import org.lecturestudio.web.api.message.util.MessageUtil;
 import org.lecturestudio.web.api.model.UserInfo;
 
 public class ViewUtil {
@@ -43,21 +44,7 @@ public class ViewUtil {
 	 */
 	public static <T extends MessagePanel> T createMessageView(Class<T> c,
 			UserInfo userInfo, UserMessage message, Dictionary dict) {
-		String myId = userInfo.getUserId();
-		boolean byMe = Objects.equals(message.getUserId(), myId);
-		String sender;
-
-		if (byMe) {
-			sender = dict.get("text.message.me");
-		}
-		else {
-			String nameFull = message.getFirstName() + " " + message.getFamilyName();
-			String[] nameParts = nameFull.split(" ");
-			String firstName = nameParts.length > 0 ? nameParts[0] : "";
-			String lastName = nameParts.length > 1 ? nameParts[nameParts.length - 1] : "";
-
-			sender = String.format("%s %s", firstName, lastName);
-		}
+		String sender = MessageUtil.evaluateSender(message, userInfo, dict);
 
 		try {
 			T view = c.getDeclaredConstructor(Dictionary.class)
@@ -71,6 +58,7 @@ public class ViewUtil {
 			throw new RuntimeException(e);
 		}
 	}
+
 	/**
 	 * Creates a concrete NotesPanel specified by the provided class
 	 * parameter.
@@ -91,5 +79,4 @@ public class ViewUtil {
 			throw new RuntimeException(e);
 		}
 	}
-
 }

lect-presenter-swing/src/main/java/org/lecturestudio/presenter/swing/view/SwingMessengerWindow.java

@@ -22,6 +22,7 @@ import java.awt.Component;
 import java.awt.Container;
 import java.awt.event.WindowAdapter;
 import java.awt.event.WindowEvent;
+import java.util.Optional;
 
 import javax.inject.Inject;
 import javax.swing.JFrame;
@@ -31,13 +32,14 @@ import org.lecturestudio.core.view.Action;
 import org.lecturestudio.presenter.api.service.UserPrivilegeService;
 import org.lecturestudio.presenter.api.view.MessengerWindow;
 import org.lecturestudio.presenter.swing.utils.ViewUtil;
+import org.lecturestudio.swing.components.MessageAsReplyView;
 import org.lecturestudio.swing.components.MessageView;
 import org.lecturestudio.swing.components.SpeechRequestView;
 import org.lecturestudio.swing.util.SwingUtils;
 import org.lecturestudio.swing.view.SwingView;
-import org.lecturestudio.web.api.message.MessengerDirectMessage;
 import org.lecturestudio.web.api.message.MessengerMessage;
 import org.lecturestudio.web.api.message.SpeechRequestMessage;
+import org.lecturestudio.web.api.message.util.MessageUtil;
 import org.lecturestudio.web.api.model.UserInfo;
 
 @SwingView(name = "messenger-window")
@@ -65,23 +67,11 @@ public class SwingMessengerWindow extends JFrame implements MessengerWindow {
 			UserInfo userInfo = userPrivilegeService.getUserInfo();
 
 			MessageView messageView = ViewUtil.createMessageView(MessageView.class, userInfo, message, dict);
-			messageView.setMessage(message.getMessage().getText());
+			messageView.setMessage(message, userInfo);
 			messageView.setOnDiscard(() -> {
 				removeMessageView(messageView);
 			});
 
-			if (message instanceof MessengerDirectMessage) {
-				MessengerDirectMessage directMessage = (MessengerDirectMessage) message;
-				String recipient = directMessage.getRecipientId();
-
-				if (recipient.equals("organisers")) {
-					messageView.setPrivateText(dict.get("text.message.to.organisators"));
-				}
-				else {
-					messageView.setPrivateText(dict.get("text.message.privately"));
-				}
-			}
-
 			messageView.pack();
 
 			messageViewContainer.add(messageView);
@@ -89,6 +79,49 @@ public class SwingMessengerWindow extends JFrame implements MessengerWindow {
 		});
 	}
 
+	@Override
+	public void setMessengerMessageAsReply(MessengerMessage message, MessengerMessage messageToReplyTo) {
+		SwingUtils.invoke(() -> {
+			UserInfo userInfo = userPrivilegeService.getUserInfo();
+
+			MessageAsReplyView messageView = ViewUtil.createMessageView(MessageAsReplyView.class, userInfo, message, dict);
+			messageView.setMessage(message, userInfo);
+
+			final String userToReplyTo = MessageUtil.evaluateSenderOfMessageToReplyTo(messageToReplyTo, userInfo, dict);
+			messageView.setUserToReplyTo(userToReplyTo);
+
+			messageView.setOnDiscard(() -> {
+				removeMessageView(messageView);
+			});
+
+			messageView.pack();
+
+			messageViewContainer.add(messageView);
+			messageViewContainer.revalidate();
+		});
+	}
+
+	@Override
+	public void setModifiedMessengerMessage(MessengerMessage modifiedMessage) {
+		SwingUtils.invoke(() -> {
+			final Optional<MessageView> toModify = findCorrespondingMessageView(modifiedMessage.getMessageId());
+
+			if (toModify.isEmpty()) {
+				return;
+			}
+
+			UserInfo userInfo = userPrivilegeService.getUserInfo();
+
+			toModify.get().setMessage(modifiedMessage, userInfo);
+			toModify.get().setIsEdited();
+		});
+	}
+
+	@Override
+	public void removeMessengerMessage(String messageId) {
+		removeMessageView(messageId);
+	}
+
 	@Override
 	public void setSpeechRequestMessage(SpeechRequestMessage message) {
 		SwingUtils.invoke(() -> {
@@ -148,4 +181,28 @@ public class SwingMessengerWindow extends JFrame implements MessengerWindow {
 			}
 		}
 	}
+
+	private void removeMessageView(final String messageId) {
+		for(Component component : messageViewContainer.getComponents()) {
+			if((component instanceof MessageView messageView) &&
+					messageView.getMessageId().equals(messageId)) {
+				
+				messageViewContainer.remove(component);
+				messageViewContainer.validate();
+				messageViewContainer.repaint();
+				
+				return;
+			}
+		}
+	}
+
+	private Optional<MessageView> findCorrespondingMessageView(final String messageId) {
+		for (Component component : messageViewContainer.getComponents()) {
+			if ((component instanceof MessageView messageView) &&
+					messageView.getMessageId().equals(messageId)) {
+				return Optional.of(messageView);
+			}
+		}
+		return Optional.empty();
+	}
 }

lect-presenter-swing/src/main/java/org/lecturestudio/presenter/swing/view/SwingSlidesView.java

@@ -50,12 +50,12 @@ import java.awt.event.ComponentEvent;
 import java.awt.event.MouseAdapter;
 import java.awt.event.MouseEvent;
 import java.awt.image.BufferedImage;
-import java.text.MessageFormat;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Enumeration;
 import java.util.List;
 import java.util.Objects;
+import java.util.Optional;
 import java.util.UUID;
 import java.util.function.Consumer;
 import java.util.function.IntSupplier;
@@ -87,6 +87,7 @@ import org.lecturestudio.presenter.swing.utils.ViewUtil;
 import org.lecturestudio.stylus.awt.AwtStylusManager;
 import org.lecturestudio.swing.components.AdaptiveTabbedPane;
 import org.lecturestudio.swing.components.ExternalFrame;
+import org.lecturestudio.swing.components.MessageAsReplyView;
 import org.lecturestudio.swing.components.MessagePanel;
 import org.lecturestudio.swing.components.MessageView;
 import org.lecturestudio.swing.components.NotesView;
@@ -113,9 +114,9 @@ import org.lecturestudio.swing.view.SwingView;
 import org.lecturestudio.swing.view.ViewPostConstruct;
 import org.lecturestudio.web.api.event.PeerStateEvent;
 import org.lecturestudio.web.api.event.RemoteVideoFrameEvent;
-import org.lecturestudio.web.api.message.MessengerDirectMessage;
 import org.lecturestudio.web.api.message.MessengerMessage;
 import org.lecturestudio.web.api.message.SpeechBaseMessage;
+import org.lecturestudio.web.api.message.util.MessageUtil;
 import org.lecturestudio.web.api.model.UserInfo;
 import org.lecturestudio.web.api.stream.model.CourseParticipant;
 
@@ -744,10 +745,37 @@ public class SwingSlidesView extends JPanel implements SlidesView {
 	public void setMessengerMessage(MessengerMessage message) {
 		SwingUtils.invoke(() -> {
 			UserInfo userInfo = userPrivilegeService.getUserInfo();
-			String myId = userInfo.getUserId();
 
 			MessageView messageView = ViewUtil.createMessageView(MessageView.class, userInfo, message, dict);
-			messageView.setMessage(message.getMessage().getText());
+			messageView.setMessage(message, userInfo);
+			messageView.setOnDiscard(() -> {
+				executeAction(discardMessageAction, messageView.getMessage());
+
+				removeMessageView(messageView);
+			});
+			messageView.setOnCreateSlide(() -> {
+				createMessageSlideAction.execute(messageView.getMessage());
+
+				removeMessageView(messageView);
+			});
+
+			messageView.pack();
+
+			addMessageView(messageView);
+		});
+	}
+
+	@Override
+	public void setMessengerMessageAsReply(MessengerMessage message, MessengerMessage messageToReplyTo) {
+		SwingUtils.invoke(() -> {
+			UserInfo userInfo = userPrivilegeService.getUserInfo();
+
+			MessageAsReplyView messageView = ViewUtil.createMessageView(MessageAsReplyView.class, userInfo, message, dict);
+			messageView.setMessage(message, userInfo);
+
+			final String userToReplyTo = MessageUtil.evaluateSenderOfMessageToReplyTo(messageToReplyTo, userInfo, dict);
+			messageView.setUserToReplyTo(userToReplyTo);
+
 			messageView.setOnDiscard(() -> {
 				executeAction(discardMessageAction, message);
 
@@ -759,32 +787,37 @@ public class SwingSlidesView extends JPanel implements SlidesView {
 				removeMessageView(messageView);
 			});
 
-			if (message instanceof MessengerDirectMessage directMessage) {
-				String recipientId = directMessage.getRecipientId();
-				boolean byMe = Objects.equals(message.getUserId(), myId);
-				boolean toMe = Objects.equals(recipientId, myId);
-				boolean toOrganisers = Objects.equals(recipientId, "organisers");
-
-				String sender = byMe
-						? dict.get("text.message.me")
-						: String.format("%s %s", message.getFirstName(), message.getFamilyName());
-
-				String recipient = toMe
-						? dict.get("text.message.to.me")
-						: toOrganisers
-						? dict.get("text.message.to.organisators.short")
-						: String.format("%s %s", directMessage.getRecipientFirstName(), directMessage.getRecipientFamilyName());
-
-				messageView.setUserName(MessageFormat.format(dict.get("text.message.recipient"), sender, ""));
-				messageView.setPrivateText(recipient);
-			}
-
 			messageView.pack();
 
 			addMessageView(messageView);
 		});
 	}
 
+	@Override
+	public void setModifiedMessengerMessage(MessengerMessage modifiedMessage) {
+		SwingUtils.invoke(() -> {
+			final Optional<MessageView> toModify = findCorrespondingMessageView(modifiedMessage.getMessageId());
+
+			if (toModify.isEmpty()){
+				return;
+			}
+
+			UserInfo userInfo = userPrivilegeService.getUserInfo();
+
+			toModify.get().setMessage(modifiedMessage, userInfo);
+			toModify.get().setIsEdited();
+		});
+	}
+
+	@Override
+	public void removeMessengerMessage(String messageId) {
+		final Optional<MessageView> toRemove = findCorrespondingMessageView(messageId);
+
+		if(toRemove.isEmpty()) return;
+
+		removeMessageView(toRemove.get());
+	}
+
 	@Override
 	public void addSpeechRequest(SpeechBaseMessage message) {
 		SwingUtils.invoke(() -> {
@@ -2411,6 +2444,16 @@ public class SwingSlidesView extends JPanel implements SlidesView {
 		}
 	}
 
+	private Optional<MessageView> findCorrespondingMessageView(final String messageId) {
+		for(Component component : messageViewContainer.getComponents()) {
+			if((component instanceof MessageView messageView) &&
+					messageView.getMessageId().equals(messageId)) {
+				return Optional.of(messageView);
+			}
+		}
+		return Optional.empty();
+	}
+
 	/**
 	 * Removes all notes from the View
 	 */

lect-swing/src/main/java/org/lecturestudio/swing/components/AdaptiveTabbedPane.java

@@ -17,6 +17,7 @@ import java.util.List;
 import java.util.stream.IntStream;
 
 public class AdaptiveTabbedPane extends JComponent {
+
 	public static final int TAB_SIZE_OFFSET = UIScale.scale(1);
 
 	private AdaptiveTabType defaultTabType = AdaptiveTabType.NORMAL;
@@ -44,8 +45,12 @@ public class AdaptiveTabbedPane extends JComponent {
 	public AdaptiveTabbedPane(int tabPlacement) {
 		setBorder(new EmptyBorder(0, 0, 0, 0));
 		setLayout(new BorderLayout());
+
+		tabbedPane.setFocusable(false);
 		tabbedPane.setTabPlacement(tabPlacement);
+
 		add(tabbedPane);
+
 		tabbedPane.addMouseListener(new MouseAdapter() {
 			@Override
 			public void mousePressed(MouseEvent e) {

lect-swing/src/main/java/org/lecturestudio/swing/components/MessageAsReplyView.java

@@ -0,0 +1,49 @@
+package org.lecturestudio.swing.components;
+
+import org.lecturestudio.core.app.dictionary.Dictionary;
+
+import java.awt.Font;
+import javax.swing.JLabel;
+import javax.swing.Box;
+
+public class MessageAsReplyView extends MessageView {
+
+    private JLabel userToReplyToLabel;
+
+    private JLabel replyToLabel;
+
+
+    public MessageAsReplyView(Dictionary dict) {
+        super(dict);
+    }
+
+    public void setUserToReplyTo(final String userToReplyTo) {
+        userToReplyToLabel.setText(userToReplyTo);
+    }
+
+    @Override
+    protected Box createUserPanel() {
+        final Box userPanel = Box.createHorizontalBox();
+
+        userPanel.setOpaque(false);
+        userPanel.add(userLabel);
+        userPanel.add(Box.createHorizontalStrut(20));
+        userPanel.add(replyToLabel);
+        userPanel.add(Box.createHorizontalStrut(20));
+        userPanel.add(userToReplyToLabel);
+        userPanel.add(privateLabel);
+        userPanel.add(Box.createHorizontalGlue());
+
+        return userPanel;
+    }
+
+    @Override
+    protected void initComponents() {
+        super.initComponents();
+
+        userToReplyToLabel = new JLabel();
+
+        replyToLabel = new JLabel(dict.get("label.reply"));
+        replyToLabel.setFont(replyToLabel.getFont().deriveFont(Font.ITALIC));
+    }
+}

lect-swing/src/main/java/org/lecturestudio/swing/components/MessagePanel.java

@@ -49,6 +49,8 @@ public abstract class MessagePanel extends JPanel {
 
 	protected JLabel privateLabel;
 
+	protected JLabel editedLabel;
+
 
 	abstract protected void createContent(JPanel content);
 
@@ -118,6 +120,11 @@ public abstract class MessagePanel extends JPanel {
 		privateLabel.setForeground(Color.RED);
 		privateLabel.setVisible(false);
 
+		editedLabel = new JLabel();
+		editedLabel.setText(dict.get("label.edited"));
+		editedLabel.setFont(editedLabel.getFont().deriveFont(Font.BOLD));
+		editedLabel.setVisible(false);
+
 		createContent(content);
 
 		add(content);

lect-swing/src/main/java/org/lecturestudio/swing/components/MessageView.java

@@ -23,6 +23,8 @@ import java.awt.Dimension;
 import java.awt.Insets;
 import java.awt.event.ComponentAdapter;
 import java.awt.event.ComponentEvent;
+import java.text.MessageFormat;
+import java.util.Objects;
 
 import javax.swing.BorderFactory;
 import javax.swing.Box;
@@ -34,22 +36,80 @@ import org.lecturestudio.core.app.dictionary.Dictionary;
 import org.lecturestudio.core.view.Action;
 import org.lecturestudio.swing.AwtResourceLoader;
 import org.lecturestudio.swing.util.SwingUtils;
+import org.lecturestudio.web.api.message.MessengerDirectMessage;
+import org.lecturestudio.web.api.message.MessengerDirectMessageAsReply;
+import org.lecturestudio.web.api.message.MessengerMessage;
+import org.lecturestudio.web.api.model.UserInfo;
 
 public class MessageView extends MessagePanel {
 
+	private MessengerMessage message;
+
 	private JButton discardButton;
 
-	private JTextArea textArea;
-
 	private JButton createSlideButton;
 
+	private String messageId;
+
+	protected JTextArea textArea;
+
 
 	public MessageView(Dictionary dict) {
 		super(dict);
 	}
 
-	public void setMessage(String message) {
-		textArea.setText(message);
+	public MessengerMessage getMessage() {
+		return message;
+	}
+
+	public void setMessage(MessengerMessage message, UserInfo userInfo) {
+		this.message = message;
+
+		textArea.setText(message.getMessage().getText());
+		messageId = message.getMessageId();
+
+		if (message instanceof MessengerDirectMessage directMessage) {
+			String myId = userInfo.getUserId();
+			String recipientId = directMessage.getRecipientId();
+
+			boolean byMe = Objects.equals(message.getUserId(), myId);
+			boolean toMe = Objects.equals(recipientId, myId);
+			boolean toOrganisers = Objects.equals(recipientId, "organisers");
+
+			String sender = byMe
+					? dict.get("text.message.me")
+					: String.format("%s %s", message.getFirstName(), message.getFamilyName());
+
+			String recipient = toMe
+					? dict.get("text.message.to.me")
+					: toOrganisers
+					? dict.get("text.message.to.organisators.short")
+					: String.format("%s %s", directMessage.getRecipientFirstName(), directMessage.getRecipientFamilyName());
+
+			setUserName(MessageFormat.format(dict.get("text.message.recipient"), sender, ""));
+			setPrivateText(recipient);
+		}
+		if (message instanceof MessengerDirectMessageAsReply directMessageAsReply) {
+			String myId = userInfo.getUserId();
+			String recipientId = directMessageAsReply.getRecipientId();
+
+			boolean byMe = Objects.equals(message.getUserId(), myId);
+			boolean toMe = Objects.equals(recipientId, myId);
+			boolean toOrganisers = Objects.equals(recipientId, "organisers");
+
+			String sender = byMe
+					? dict.get("text.message.me")
+					: String.format("%s %s", message.getFirstName(), message.getFamilyName());
+
+			String recipient = toMe
+					? dict.get("text.message.to.me")
+					: toOrganisers
+					? dict.get("text.message.to.organisators.short")
+					: String.format("%s %s", directMessageAsReply.getRecipientFirstName(), directMessageAsReply.getRecipientFamilyName());
+
+			setUserName(MessageFormat.format(dict.get("text.message.recipient"), sender, ""));
+			setPrivateText(recipient);
+		}
 	}
 
 	public void setPrivateText(String text) {
@@ -65,29 +125,32 @@ public class MessageView extends MessagePanel {
 		SwingUtils.bindAction(createSlideButton, action);
 	}
 
+	public String getMessageId() {
+		return messageId;
+	}
+
+	public void setIsEdited() {
+		editedLabel.setVisible(true);
+	}
+
 	@Override
 	protected void createContent(JPanel content) {
-		discardButton = new JButton(AwtResourceLoader.getIcon("message-check.svg", 18));
-		discardButton.setToolTipText(dict.get("button.processed"));
-		createSlideButton = new JButton(AwtResourceLoader.getIcon("message-slide.svg", 18));
-		createSlideButton.setToolTipText(dict.get("button.create.slide"));
+		initComponents();
 
-		Box userPanel = Box.createHorizontalBox();
-		userPanel.setOpaque(false);
-		userPanel.add(userLabel);
-		userPanel.add(privateLabel);
-		userPanel.add(Box.createHorizontalGlue());
+		Box userPanel = createUserPanel();
 
-		Box timePanel = Box.createHorizontalBox();
-		timePanel.setOpaque(false);
-		timePanel.add(timeLabel);
-		timePanel.add(Box.createHorizontalGlue());
+		Box timeEditedPanel = Box.createHorizontalBox();
+		timeEditedPanel.setOpaque(false);
+		timeEditedPanel.add(timeLabel);
+		timeEditedPanel.add(Box.createHorizontalStrut(10));
+		timeEditedPanel.add(editedLabel);
+		timeEditedPanel.add(Box.createHorizontalGlue());
 
 		Box userTimePanel = Box.createVerticalBox();
 		userTimePanel.setBorder(BorderFactory.createEmptyBorder());
 		userTimePanel.setOpaque(false);
 		userTimePanel.add(userPanel);
-		userTimePanel.add(timePanel);
+		userTimePanel.add(timeEditedPanel);
 
 		Box controlPanel = Box.createHorizontalBox();
 		controlPanel.setBorder(BorderFactory.createEmptyBorder(2, 5, 2, 5));
@@ -133,4 +196,23 @@ public class MessageView extends MessagePanel {
 			}
 		});
 	}
+
+	protected Box createUserPanel() {
+		final Box userPanel = Box.createHorizontalBox();
+
+		userPanel.setOpaque(false);
+		userPanel.add(userLabel);
+		userPanel.add(privateLabel);
+		userPanel.add(Box.createHorizontalGlue());
+
+		return userPanel;
+	}
+
+	protected void initComponents() {
+		discardButton = new JButton(AwtResourceLoader.getIcon("message-check.svg", 18));
+		createSlideButton = new JButton(AwtResourceLoader.getIcon("message-slide.svg", 18));
+
+		discardButton.setToolTipText(dict.get("button.processed"));
+		createSlideButton.setToolTipText(dict.get("button.create.slide"));
+	}
 }

lect-swing/src/main/java/org/lecturestudio/swing/components/ParticipantList.java

@@ -62,13 +62,13 @@ public class ParticipantList extends JPanel {
 	@Inject
 	public ParticipantList(ResourceBundle bundle) {
 		super();
-		actionMap = new HashMap<>();
 
 		setLayout(new BorderLayout());
 		setFocusable(false);
 		setIgnoreRepaint(true);
 
 		listModel = new SortedListModel();
+		actionMap = new HashMap<>();
 
 		popupMenuBanItem = new JMenuItem("Ban");
 		popupMenuBanItem.addActionListener(e -> {

lect-swing/src/main/java/org/lecturestudio/swing/components/ThumbPanel.java

@@ -455,7 +455,8 @@ public class ThumbPanel extends JPanel {
 			if (selected) {
 				g2d.setColor(Color.BLUE);
 				g2d.fillRect(0, 0, getWidth(), getHeight());
-			}else if(page.isOverlay()){
+			}
+			else if (page.isOverlay()) {
 				g2d.setColor(Color.GRAY);
 				g2d.fillRect(0, 0, getWidth(), getHeight());
 			}

lect-web-api/pom.xml

@@ -175,7 +175,7 @@
 		<dependency>
 			<groupId>org.apache.tomcat.embed</groupId>
 			<artifactId>tomcat-embed-websocket</artifactId>
-			<version>10.1.10</version>
+			<version>10.1.19</version>
 		</dependency>
 		<dependency>
 			<groupId>org.springframework</groupId>

lect-web-api/src/main/java/org/lecturestudio/web/api/data/bind/MessengerMessageAdapter.java

@@ -27,7 +27,9 @@ import javax.json.JsonValue;
 import javax.json.bind.adapter.JsonbAdapter;
 
 import org.lecturestudio.web.api.message.MessengerDirectMessage;
+import org.lecturestudio.web.api.message.MessengerDirectMessageAsReply;
 import org.lecturestudio.web.api.message.MessengerMessage;
+import org.lecturestudio.web.api.message.MessengerMessageAsReply;
 import org.lecturestudio.web.api.model.Message;
 
 public class MessengerMessageAdapter implements JsonbAdapter<MessengerMessage, JsonObject> {
@@ -43,12 +45,20 @@ public class MessengerMessageAdapter implements JsonbAdapter<MessengerMessage, J
 		builder.add("date", message.getDate().toString());
 		builder.add("messageId", message.getMessageId());
 
+		if(message instanceof MessengerMessageAsReply messageAsReply) {
+			builder.add("msgIdToReplyTo", messageAsReply.getMsgIdToReplyTo());
+		}
+
 		if (message instanceof MessengerDirectMessage directMessage) {
 			builder.add("recipientId", directMessage.getRecipientId());
 			builder.add("recipientFirstName", directMessage.getRecipientFirstName());
 			builder.add("recipientFamilyName", directMessage.getRecipientFamilyName());
 		}
 
+		if(message instanceof MessengerDirectMessageAsReply directMessageAsReply) {
+			builder.add("msgIdToReplyTo", directMessageAsReply.getMsgIdToReplyTo());
+		}
+
 		return builder.build();
 	}
 
@@ -58,21 +68,45 @@ public class MessengerMessageAdapter implements JsonbAdapter<MessengerMessage, J
 
 		MessengerMessage message;
 
-		if (type.equals("MessengerDirectMessage")) {
-			MessengerDirectMessage directMessage = new MessengerDirectMessage();
-			directMessage.setRecipientId(jsonObject.getString("recipientId"));
+		switch (type) {
+			case "MessengerDirectMessage" -> {
+				MessengerDirectMessage directMessage = new MessengerDirectMessage();
 
-			if (!jsonObject.isNull("recipientFirstName")) {
-				directMessage.setRecipientFirstName(jsonObject.getString("recipientFirstName"));
-			}
-			if (!jsonObject.isNull("recipientFamilyName")) {
-				directMessage.setRecipientFamilyName(jsonObject.getString("recipientFamilyName"));
+				directMessage.setRecipientId(jsonObject.getString("recipientId"));
+				if (!jsonObject.isNull("recipientFirstName")) {
+					directMessage.setRecipientFirstName(jsonObject.getString("recipientFirstName"));
+				}
+				if (!jsonObject.isNull("recipientFamilyName")) {
+					directMessage.setRecipientFamilyName(jsonObject.getString("recipientFamilyName"));
+				}
+				message = directMessage;
 			}
+			case "MessengerDirectMessageAsReply" -> {
+				MessengerDirectMessageAsReply directMessageAsReply = new MessengerDirectMessageAsReply();
 
-			message = directMessage;
-		}
-		else {
-			message = new MessengerMessage();
+				directMessageAsReply.setRecipientId(jsonObject.getString("recipientId"));
+				if (!jsonObject.isNull("recipientFirstName")) {
+					directMessageAsReply.setRecipientFirstName(jsonObject.getString("recipientFirstName"));
+				}
+				if (!jsonObject.isNull("recipientFamilyName")) {
+					directMessageAsReply.setRecipientFamilyName(jsonObject.getString("recipientFamilyName"));
+				}
+				if (!jsonObject.isNull("messageIdToReplyTo")) {
+					directMessageAsReply.setMsgIdToReplyTo(jsonObject.getString("msgIdToReplyTo"));
+				}
+
+				message = directMessageAsReply;
+			}
+			case "MessengerMessageAsReply" -> {
+				MessengerMessageAsReply messageAsReply = new MessengerMessageAsReply();
+
+				if (!jsonObject.isNull("msgIdToReplyTo")) {
+					messageAsReply.setMsgIdToReplyTo(jsonObject.getString("msgIdToReplyTo"));
+				}
+
+				message = messageAsReply;
+			}
+			default -> message = new MessengerMessage();
 		}
 
 		if (jsonObject.get("text").getValueType() != JsonValue.ValueType.NULL) {
@@ -96,6 +130,12 @@ public class MessengerMessageAdapter implements JsonbAdapter<MessengerMessage, J
 		if (jsonObject.get("messageId").getValueType() != JsonValue.ValueType.NULL) {
 			message.setMessageId(jsonObject.getString("messageId"));
 		}
+		if (jsonObject.get("deleted").getValueType() != JsonValue.ValueType.NULL) {
+			message.setDeleted(jsonObject.getBoolean("deleted"));
+		}
+		if (jsonObject.get("edited").getValueType() != JsonValue.ValueType.NULL) {
+			message.setEdited(jsonObject.getBoolean("edited"));
+		}
 
 		return message;
 	}

lect-web-api/src/main/java/org/lecturestudio/web/api/data/bind/StopStreamEnvironmentMessageAdapter.java

@@ -0,0 +1,45 @@
+package org.lecturestudio.web.api.data.bind;
+
+import static java.util.Objects.nonNull;
+
+import javax.json.Json;
+import javax.json.JsonObject;
+import javax.json.JsonObjectBuilder;
+import javax.json.bind.adapter.JsonbAdapter;
+
+import org.lecturestudio.web.api.message.StopStreamEnvironmentMessage;
+
+import java.time.ZonedDateTime;
+
+public class StopStreamEnvironmentMessageAdapter implements JsonbAdapter<StopStreamEnvironmentMessage, JsonObject> {
+
+    @Override
+    public JsonObject adaptToJson(StopStreamEnvironmentMessage stopStreamEnvironmentMessage) throws Exception {
+        JsonObjectBuilder builder = Json.createObjectBuilder();
+
+        builder.add("type", stopStreamEnvironmentMessage.getClass().getSimpleName());
+
+        if (nonNull(stopStreamEnvironmentMessage.getMessageId())) {
+            builder.add("messageId", stopStreamEnvironmentMessage.getMessageId());
+        }
+
+        return builder.build();
+    }
+
+    @Override
+    public org.lecturestudio.web.api.message.StopStreamEnvironmentMessage adaptFromJson(JsonObject jsonObject) throws Exception {
+        String typeStr = jsonObject.getString("type");
+        String className = StopStreamEnvironmentMessage.class.getPackageName() + "." + typeStr;
+        Class<?> cls = Class.forName(className);
+
+        StopStreamEnvironmentMessage message = (StopStreamEnvironmentMessage) cls.getConstructor().newInstance();
+
+        message.setMessageId(jsonObject.getString("messageId"));
+        message.setDate(ZonedDateTime.parse(jsonObject.getString("time")));
+        message.setUserId(jsonObject.getString("userId"));
+        message.setFirstName(jsonObject.getString("firstName"));
+        message.setFamilyName(jsonObject.getString("familyName"));
+
+        return message;
+    }
+}

lect-web-api/src/main/java/org/lecturestudio/web/api/message/MessengerDirectMessageAsReply.java

@@ -0,0 +1,14 @@
+package org.lecturestudio.web.api.message;
+
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.Setter;
+
+@Getter
+@Setter
+@NoArgsConstructor
+public class MessengerDirectMessageAsReply extends MessengerDirectMessage {
+
+    private String msgIdToReplyTo;
+
+}

lect-web-api/src/main/java/org/lecturestudio/web/api/message/MessengerMessage.java

@@ -31,4 +31,7 @@ public class MessengerMessage extends UserMessage {
 
 	private Message message;
 
+	private boolean deleted;
+
+	private boolean edited;
 }

lect-web-api/src/main/java/org/lecturestudio/web/api/message/MessengerMessageAsReply.java

@@ -0,0 +1,14 @@
+package org.lecturestudio.web.api.message;
+
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.Setter;
+
+@Getter
+@Setter
+@NoArgsConstructor
+public class MessengerMessageAsReply extends MessengerMessage {
+
+    private String msgIdToReplyTo;
+
+}

lect-web-api/src/main/java/org/lecturestudio/web/api/message/StopStreamEnvironmentMessage.java

@@ -0,0 +1,5 @@
+package org.lecturestudio.web.api.message;
+
+public class StopStreamEnvironmentMessage extends UserMessage {
+
+}

lect-web-api/src/main/java/org/lecturestudio/web/api/message/WebMessage.java

@@ -33,4 +33,12 @@ public abstract class WebMessage {
 
 	private ZonedDateTime date;
 
+
+	@Override
+	public boolean equals(final Object obj) {
+		if(!(obj instanceof WebMessage webMessage)) return false;
+
+		return this == webMessage || this.messageId.equals(webMessage.getMessageId());
+	}
+
 }

lect-web-api/src/main/java/org/lecturestudio/web/api/message/WebSocketStompTransport.java

@@ -96,7 +96,8 @@ public class WebSocketStompTransport extends ExecutableBase implements MessageTr
 				new CoursePresenceMessageAdapter(),
 				new MessengerMessageAdapter(),
 				new QuizAnswerMessageAdapter(),
-				new SpeechMessageAdapter()
+				new SpeechMessageAdapter(),
+				new StopStreamEnvironmentMessageAdapter()
 		);
 
 		jsonb = JsonbBuilder.create(jsonbConfig);
@@ -255,6 +256,9 @@ public class WebSocketStompTransport extends ExecutableBase implements MessageTr
 
 			subscribe(stompSession, "/topic/course/event/{id}/presence");
 			subscribe(stompSession, "/topic/course/{id}/chat");
+			subscribe(stompSession, "/topic/course/{id}/chat/deletion");
+			subscribe(stompSession, "/topic/course/{id}/chat/edit");
+			subscribe(stompSession, "/topic/course/{id}/stopStreamEnvironment");
 			subscribe(stompSession, "/user/queue/course/{id}/chat");
 			subscribe(stompSession, "/user/queue/course/{id}/presence");
 			subscribe(stompSession, "/user/queue/course/{id}/speech");

lect-web-api/src/main/java/org/lecturestudio/web/api/message/util/MessageUtil.java

@@ -0,0 +1,72 @@
+package org.lecturestudio.web.api.message.util;
+
+import org.lecturestudio.core.app.dictionary.Dictionary;
+import org.lecturestudio.web.api.message.MessengerDirectMessageAsReply;
+import org.lecturestudio.web.api.message.MessengerMessage;
+import org.lecturestudio.web.api.message.MessengerMessageAsReply;
+import org.lecturestudio.web.api.message.UserMessage;
+import org.lecturestudio.web.api.model.UserInfo;
+
+import java.util.List;
+import java.util.Objects;
+
+public class MessageUtil {
+
+    public static boolean isReply(final UserMessage message) {
+        return message instanceof MessengerMessageAsReply || message instanceof MessengerDirectMessageAsReply;
+    }
+
+    public static String evaluateSender(final UserMessage message, final UserInfo userInfo, final Dictionary dictionary) {
+        final boolean byMe = sentByMe(message, userInfo);
+
+        if (byMe) return dictionary.get("text.message.me");
+        else {
+            String nameFull = message.getFirstName() + " " + message.getFamilyName();
+            String[] nameParts = nameFull.split(" ");
+            String firstName = nameParts.length > 0 ? nameParts[0] : "";
+            String lastName = nameParts.length > 1 ? nameParts[nameParts.length - 1] : "";
+
+            return String.format("%s %s", firstName, lastName);
+        }
+    }
+
+    public static String evaluateSenderOfMessageToReplyTo(final UserMessage messageToReplyTo, final UserInfo userInfo, final Dictionary dictionary) {
+        final boolean byMe = sentByMe(messageToReplyTo, userInfo);
+
+        if(byMe) return dictionary.get("text.message.me.dative");
+
+        return evaluateSender(messageToReplyTo, userInfo, dictionary);
+    }
+
+    public static MessengerMessage findMessageToReplyTo(final List<MessengerMessage> messages, final MessengerMessage message) {
+        if(message instanceof MessengerMessageAsReply messageAsReply) {
+            return messages.stream()
+                    .filter(messengerMessage -> messengerMessage.getMessageId().equals(messageAsReply.getMsgIdToReplyTo()))
+                    .findAny()
+                    .orElseThrow(() -> new IllegalArgumentException("Given ID of message to reply to couldn't be found"));
+        }
+
+        if(message instanceof MessengerDirectMessageAsReply directMessageAsReply) {
+            return messages.stream()
+                    .filter(messengerMessage -> messengerMessage.getMessageId().equals(directMessageAsReply.getMsgIdToReplyTo()))
+                    .findAny()
+                    .orElseThrow(() -> new IllegalArgumentException("Given ID of message to reply to couldn't be found"));
+        }
+
+        return null;
+    }
+
+    public static void updateOutdatedMessage(final List<MessengerMessage> messages, final MessengerMessage newMessage) {
+		for (MessengerMessage message : messages) {
+			if (message.getMessageId().equals(newMessage.getMessageId())) {
+				messages.remove(message);
+				messages.add(newMessage);
+			}
+		}
+    }
+
+    private static boolean sentByMe(final UserMessage message, final UserInfo userInfo) {
+        final String myId = userInfo.getUserId();
+        return Objects.equals(message.getUserId(), myId);
+    }
+}

lect-web-api/src/main/java/org/lecturestudio/web/api/model/Message.java

@@ -39,6 +39,14 @@ public class Message extends ServiceModel {
 		this.text = text;
 	}
 
+	public boolean isReply() {
+		return false;
+	}
+
+	public String getMsgIdToReplyTo() {
+		return null;
+	}
+
 	@Override
 	public String toString() {
 		return getClass().getSimpleName() + ": " + text;

lect-web-api/src/main/java/org/lecturestudio/web/api/model/MessageAsReply.java

@@ -0,0 +1,33 @@
+package org.lecturestudio.web.api.model;
+
+public class MessageAsReply extends Message {
+
+    private String msgIdToReplyTo;
+
+
+    public MessageAsReply() {
+        this(null);
+    }
+
+    public MessageAsReply(String msgIdToReplyTo) {
+        setMsgIdToReplyTo(msgIdToReplyTo);
+    }
+
+    public String getMsgIdToReplyTo() {
+        return msgIdToReplyTo;
+    }
+
+    public void setMsgIdToReplyTo(final String msgIdToReplyTo) {
+        this.msgIdToReplyTo = msgIdToReplyTo;
+    }
+
+    @Override
+    public boolean isReply() {
+        return true;
+    }
+
+    @Override
+    public String toString() {
+        return getClass().getSimpleName() + ": " + msgIdToReplyTo;
+    }
+}

lect-web-api/src/main/java/org/lecturestudio/web/api/stream/model/Course.java

@@ -25,6 +25,8 @@ public class Course {
 
 	private Long id;
 
+	private String defaultAccessLink;
+
 	private String roomId;
 
 	private String title;
@@ -36,6 +38,10 @@ public class Course {
 		return id;
 	}
 
+	public String getDefaultAccessLink() {
+		return defaultAccessLink;
+	}
+
 	public String getRoomId() {
 		return roomId;
 	}