diff --git a/src/main/java/me/mrletsplay/shareclient/ShareClient.java b/src/main/java/me/mrletsplay/shareclient/ShareClient.java
index b86557d..7e34bf4 100644
--- a/src/main/java/me/mrletsplay/shareclient/ShareClient.java
+++ b/src/main/java/me/mrletsplay/shareclient/ShareClient.java
@@ -393,6 +393,12 @@ public class ShareClient extends AbstractUIPlugin implements MessageListener, Di
 		return partListener;
 	}
 
+	public static void assertOnUIThread() {
+		if(!Thread.currentThread().equals(Display.getDefault().getThread())) {
+			MessageDialog.openError(null, "Assertion failed", "Not on UI thread");
+		}
+	}
+
 	@Override
 	public void earlyStartup() {
 	}
diff --git a/src/main/java/me/mrletsplay/shareclient/util/ShareSession.java b/src/main/java/me/mrletsplay/shareclient/util/ShareSession.java
index e2b15db..fc0bcb1 100644
--- a/src/main/java/me/mrletsplay/shareclient/util/ShareSession.java
+++ b/src/main/java/me/mrletsplay/shareclient/util/ShareSession.java
@@ -89,7 +89,8 @@ public class ShareSession {
 
 				@Override
 				public void onInsert(int index, byte character) {
-					// TODO: assert that we are on the UI thread
+					ShareClient.assertOnUIThread();
+
 					ShareClientDocumentListener documentListener = ShareClient.getDefault().getPartListener().getListener(path);
 					if(documentListener != null) {
 						IDocument document = documentListener.getDocument();
@@ -108,7 +109,8 @@ public class ShareSession {
 
 				@Override
 				public void onDelete(int index) {
-					// TODO: assert that we are on the UI thread
+					ShareClient.assertOnUIThread();
+
 					ShareClientDocumentListener documentListener = ShareClient.getDefault().getPartListener().getListener(path);
 					if(documentListener != null) {
 						IDocument document = documentListener.getDocument();
diff --git a/src/main/java/me/mrletsplay/shareclient/util/listeners/ShareClientDocumentListener.java b/src/main/java/me/mrletsplay/shareclient/util/listeners/ShareClientDocumentListener.java
index 8e1d89f..ab18f10 100644
--- a/src/main/java/me/mrletsplay/shareclient/util/listeners/ShareClientDocumentListener.java
+++ b/src/main/java/me/mrletsplay/shareclient/util/listeners/ShareClientDocumentListener.java
@@ -35,6 +35,8 @@ public class ShareClientDocumentListener implements IDocumentListener {
 
 	@Override
 	public void documentAboutToBeChanged(DocumentEvent event) {
+		ShareClient.assertOnUIThread();
+
 		if(ignoreChanges) return;
 
 		System.out.println("UPDATE ON THREAD " + Thread.currentThread());
diff --git a/src/main/java/me/mrletsplay/shareclient/views/ShareView.java b/src/main/java/me/mrletsplay/shareclient/views/ShareView.java
index 73e2544..e30aafe 100644
--- a/src/main/java/me/mrletsplay/shareclient/views/ShareView.java
+++ b/src/main/java/me/mrletsplay/shareclient/views/ShareView.java
@@ -178,6 +178,11 @@ public class ShareView extends ViewPart {
 					sb.append("--- Document: ").append(path).append('\n');
 
 					sb.append(document.getContentsAsString());
+					sb.append('\n');
+
+					for(int i = 0; i < document.getCharBag().size(); i++) {
+						sb.append(document.getCharBag().get(i)).append('\n');
+					}
 
 					sb.append('\n');
 					sb.append('\n');