public IStatus validateEdit(final IFile[] files, final FileModificationValidationContext context) {
		if (ClearCasePreferences.isCheckoutAutoNever())
			return CANCEL;
		final ClearCaseProvider provider = getProvider(files);
		final Shell shell = getShell(context);
		final boolean askForComment = ClearCasePreferences.isCommentCheckout() && !ClearCasePreferences.isCommentCheckoutNeverOnAuto();
		if (null == shell || !askForComment) {

			if (PreventCheckoutHelper.isPreventedFromCheckOut(shell, provider, files, ClearCasePreferences.isSilentPrevent())) {
				return CANCEL;
			}
			// UCM checkout.
			if (ClearCasePreferences.isUCM() && !ClearCasePreferences.isUseClearDlg()) {
				if (!UcmActivity.checkoutWithActivity(provider, files, shell))
					// no checkout
					return CANCEL;
			}
			
			return super.validateEdit(files, context);
		}
		try {
			this.validateEditLock.acquire();
			final IFile[] readOnlyFiles = getFilesToCheckout(files);
			if (readOnlyFiles.length == 0)
				return OK;
			final IStatus[] status = new IStatus[1];
			PlatformUI.getWorkbench().getDisplay().syncExec(new Runnable() {

				public void run() {
					status[0] = checkout(readOnlyFiles, shell);
				}
			});
			if (null == status[0])
				return CANCEL;
			return status[0];
		} finally {
			this.validateEditLock.release();
		}
	}

public static boolean checkoutWithActivity(ClearCaseProvider provider, IResource[] resources, Shell shell) {

		ShowActivityDialog sad = new ShowActivityDialog(shell, provider, resources);
		PlatformUI.getWorkbench().getDisplay().syncExec(sad);
		if (sad.isCheckoutAllowed()) {
			return true;

		} else {
			return false;
		}
	}

public class ShowActivityDialog implements Runnable{

	private IResource [] resources;
	
	private ClearCaseProvider provider;

	private boolean allowCheckout;

	private Shell shell;
	
	public ShowActivityDialog(Shell shell, ClearCaseProvider provider,  IResource[] resources) {
		this.shell = shell;
		this.provider = provider;
		this.resources = resources;
	}

	public void run() {
		IResource resource = resources[0];
		if (resource != null) {
			String view = ClearCaseProvider.getViewName(resource);
			ActivityDialog dlg = new ActivityDialog(shell, provider, resource);
			if (dlg.open() == Window.OK) {
				String activity = dlg.getSelectedActivity();
				if (activity != null) {
					provider.setActivity(activity, view);
					allowCheckout = true;
				}

			} else
				// Answer was N or Cancel.
				allowCheckout = false;

			allowCheckout =  true;
		}
		
	}

	

	public boolean isCheckoutAllowed() {
		return allowCheckout;
	}
}