* @return True if the graph is valid, false otherwise.
*/
private void validate() {
removeMarkers();
IFile file = ((IFileEditorInput) getEditorInput()).getFile();
IValidator validator = graph.getConfiguration().getValidator();
if (!validator.validate(graph, file)) {
// activate problems view
IWorkbenchPage page = PlatformUI.getWorkbench()
.getActiveWorkbenchWindow().getActivePage();
try {
page.showView(IPageLayout.ID_PROBLEM_VIEW);