Bug 156865 Undo / Redo marker actions not updated
I20060906-1200 If a file gets delete after adding/changing/removing a marker then the Undo and Redo actions are not updated and still show, e.g. Undo Add Task Redo Add Task Executing the undo or redo does nothing (no feedback, no .log entry) and the undo and redo menu text remains the same and enabled.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/ide/undo/AbstractWorkspaceOperation.java
protected Shell getShell(IAdaptable info) {
		if (info != null) {
			Shell shell = (Shell) info.getAdapter(Shell.class);
			if (shell != null) {
				return shell;
			}
		}
		return PlatformUI.getWorkbench().getActiveWorkbenchWindow().getShell();
	}
	/**
	 * Return whether the proposed operation is valid. The default
	 * implementation simply checks to see if the flag has been marked as
	 * invalid, relying on the workspace listener to mark the flag invalid when
	 * this operation's resources change.
	 * 
	 * Subclasses may use the implemented resource listener strategy as is to
	 * validate operations. Subclasses may also override
	 * {@link #isResourceChangeInvalidating(IResourceDelta, IResource)} or
	 * {@link #getDeltaVisitor()} to refine the resource listener strategy.
	 * Subclasses may also override this method to completely ignore the
	 * resource listener strategy and instead use their own strategy for
	 * validating resources.
	 */
	protected boolean isValid() {
		return isValid;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.core.commands.operations.IAdvancedUndoableOperation#aboutToNotify(org.eclipse.core.commands.operations.OperationHistoryEvent)