public void checkout(IResource[] resources, int depth,
			IProgressMonitor progress) throws TeamException {
		IUndoableOperation operation = new net.sourceforge.eclipseccase.CheckOutOperation(this,"checkout",resources, depth);
        
		
		IOperationHistory operationHistory = OperationHistoryFactory.getOperationHistory();
		IWorkbench wb = PlatformUI.getWorkbench();
		IUndoContext undoContext = wb.getOperationSupport().getUndoContext();
		operation.addContext(undoContext);
		
       
        try {
            operationHistory.execute(operation,progress,null);
        } catch (ExecutionException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally {
        	setComment("");
        }
		

	}

@Override
	public IStatus undo(IProgressMonitor monitor, IAdaptable info)
			throws ExecutionException {
		MessageDialog.openInformation(PlatformUI.getWorkbench().
                getActiveWorkbenchWindow().getShell(),
				"Checkout",  
				"Undoing view action");   
			return Status.OK_STATUS;
	} 

public Change perform(IProgressMonitor pm) throws CoreException {
		fUndoUntilException= null;
		List undos= new ArrayList(fChanges.size());
		pm.beginTask("", fChanges.size()); //$NON-NLS-1$
		pm.setTaskName(RefactoringCoreMessages.CompositeChange_performingChangesTask_name);
		Change change= null;
		boolean canceled= false;
		try {
			for (Iterator iter= fChanges.iterator(); iter.hasNext();) {
				change= (Change)iter.next();
				if (canceled && !internalProcessOnCancel(change))
					continue;

				if (change.isEnabled()) {
					Change undoChange= null;
					try {
						undoChange= change.perform(new SubProgressMonitor(pm, 1));
					} catch(OperationCanceledException e) {
						canceled= true;
						if (!internalContinueOnCancel())
							throw e;
						undos= null;
					}
					if (undos != null) {
						if (undoChange == null) {
							undos= null;
						} else {
							undos.add(undoChange);
						}
					}
				}
				// remove the change from the list of children to give
				// the garbage collector the change to collect the change. This
				// ensures that the memory consumption doesn't go up when
				// producing the undo change tree.
				iter.remove();
				// Make sure we dispose the change since it will now longer be
				// in the list of children when call CompositeChange#dispose()
				final Change changeToDispose= change;
				SafeRunner.run(new ISafeRunnable() {
					public void run() throws Exception {
						changeToDispose.dispose();
					}
					public void handleException(Throwable exception) {
						RefactoringCorePlugin.log(exception);
					}
				});
			}
			if (canceled)
				throw new OperationCanceledException();
			if (undos != null) {
				Collections.reverse(undos);
				return createUndoChange((Change[]) undos.toArray(new Change[undos.size()]));
			} else {
				return null;
			}
		} catch (CoreException e) {
			handleUndos(change, undos);
			internalHandleException(change, e);
			throw e;
		} catch (RuntimeException e) {
			handleUndos(change, undos);
			internalHandleException(change, e);
			throw e;
		}
	}

if (undos != null) {
						if (undoChange == null) {
							undos= null;
						} else {
							undos.add(undoChange);
						}
					}

if (undos != null) {
  if (undoChange == null) {
	undos= null;
  } else {
	undos.add(undoChange);
  }
}