TOMERGE: Fix undo menu items

Turns out I dropped a setUndoManager call somewhere, as well typed Redo
instead of Undo somewhere.

Author: matthijskooijman

app/src/processing/app/Editor.java

@@ -1496,7 +1496,7 @@ public UndoAction() {
 
     public void actionPerformed(ActionEvent e) {
       try {
-        getCurrentTab().handleRedo();
+        getCurrentTab().handleUndo();
       } catch (CannotUndoException ex) {
         //System.out.println("Unable to undo: " + ex);
         //ex.printStackTrace();

app/src/processing/app/EditorTab.java

@@ -54,6 +54,7 @@
 import org.fife.ui.rsyntaxtextarea.RSyntaxUtilities;
 import org.fife.ui.rtextarea.Gutter;
 import org.fife.ui.rtextarea.RTextScrollPane;
+import org.fife.ui.rtextarea.RUndoManager;
 
 import processing.app.helpers.DocumentTextChangeListener;
 import processing.app.syntax.ArduinoTokenMakerFactory;
@@ -108,8 +109,10 @@ public EditorTab(Editor editor, SketchFile file, String contents)
     applyPreferences();
     add(this.scrollPane, BorderLayout.CENTER);
 
-    UndoManager undo = new LastUndoableEditAwareUndoManager(this.textarea, this.editor);
-    ((RSyntaxDocument)textarea.getDocument()).addUndoableEditListener(undo);
+    RUndoManager undo = new LastUndoableEditAwareUndoManager(this.textarea,
+        this.editor);
+    document.addUndoableEditListener(undo);
+    textarea.setUndoManager(undo);
   }
 
   private RSyntaxDocument createDocument(String contents) {