fUndoChange= createReverseChange(fTextBufferEditor.performEdits(pm), getReverseKind());
editor= new TextBufferEditor(acquireTextBuffer()); addTextEdits(editor, false); fUndoChange= createReverseChange(editor.performEdits(pm), getReverseKind());
	public void perform(ChangeContext context, IProgressMonitor pm) throws JavaModelException, ChangeAbortException {		try {			fUndoChange= null;			fUndoChange= createReverseChange(fTextBufferEditor.performEdits(pm), getReverseKind());		} catch (Exception e) {			handleException(context, e);		}	}