Bug 63268 error while activating view
I'm not sure what caused this behaviour. I created a workspace this morning, imported a few projects, and ran the UI Test Suite. However, I got an error when trying to activate the Hierarchy view (by clicking on it). The error looks like an infinite loop. The trace is over 800 lines long, so I'll attach it in a minute.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/typehierarchy/TypeHierarchyViewPart.java
/**
	 * Restores the type hierarchy settings from a memento.
	 */
	private void restoreState(final IMemento memento, IJavaElement defaultInput) {
		IJavaElement input= defaultInput;
		String elementId= memento.getString(TAG_INPUT);
		if (elementId != null) {
			input= JavaCore.create(elementId);
			if (input != null && !input.exists()) {
				input= null;
			}
		}
		if (input == null) {
			doRestoreState(memento, input);
		} else {
			final IJavaElement hierarchyInput= input;
			
			synchronized (this) {
				String label= TypeHierarchyMessages.getFormattedString("TypeHierarchyViewPart.restoreinput", hierarchyInput.getElementName()); 
				fNoHierarchyShownLabel.setText(label); 
				fRestoreStateJob= new Job(label) {
					protected IStatus run(IProgressMonitor monitor) {
						try {
							doRestoreInBackground(memento, hierarchyInput, monitor);
						} catch (JavaModelException e) {
							return e.getStatus();
						} catch (OperationCanceledException e) {
							return Status.CANCEL_STATUS;
						}
						return Status.OK_STATUS;