An undoable action marks the sketh as modified

Author: Federico Fissore

app/src/processing/app/Editor.java

@@ -1697,6 +1697,7 @@ public void undoableEditHappened(UndoableEditEvent e) {
 
           } else if (undo != null) {
             undo.addEdit(new CaretAwareUndoableEdit(e.getEdit(), textarea));
+            sketch.setModified(true);
             undoAction.updateUndoState();
             redoAction.updateRedoState();
           }