Make renaming a compound change (undo by clicking undo once).

CupPlugin/src/de/tum/in/www2/cupplugin/commands/RenameSymbolHandler.java

@@ -195,8 +195,11 @@ public class RenameSymbolHandler extends AbstractHandler {
 					return null;
 				}
 
+				editor.beginCompoundChange();
 				RenamingVisitor visitor = new RenamingVisitor(doc, oldName, renameDialog.getNewName());
 				ast.accept(visitor, null);
+				editor.endCompoundChange();
+
 			}
 		}
 

CupPlugin/src/de/tum/in/www2/cupplugin/editors/CupTextEditor.java

@@ -12,6 +12,7 @@ import org.eclipse.jface.text.BadLocationException;
 import org.eclipse.jface.text.IDocument;
 import org.eclipse.jface.text.source.ISourceViewer;
 import org.eclipse.jface.text.source.IVerticalRulerInfo;
+import org.eclipse.jface.text.source.SourceViewer;
 import org.eclipse.swt.custom.StyledText;
 import org.eclipse.swt.graphics.Color;
 import org.eclipse.swt.widgets.Display;
@@ -109,6 +110,14 @@ public class CupTextEditor extends TextEditor
 		}
 	}
 
+	public void beginCompoundChange() {
+		((SourceViewer) getSourceViewer()).getUndoManager().beginCompoundChange();
+	}
+
+	public void endCompoundChange() {
+		((SourceViewer) getSourceViewer()).getUndoManager().endCompoundChange();
+	}
+	
 	public IDocument getDocument() {
 		IDocumentProvider provider = getDocumentProvider();
 		if (provider != null)