Bug 32384 Cannot open type hierarchy after a cancel
JUnit setup 1) open the type hierarchy on TestCase 2) press F4 on Object 3) cancel in progress bar 4) press F4 on Object again ->nothing happens
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/typehierarchy/TypeHierarchyViewPart.java
fHierarchyLifeCycle.removeChangedListener(fTypeHierarchyLifeCycleListener);
		fPaneLabelProvider.dispose();
		
		fMethodsViewer.dispose();
		
		if (fPropertyChangeListener != null) {
			JavaPlugin.getDefault().getPreferenceStore().removePropertyChangeListener(fPropertyChangeListener);
			fPropertyChangeListener= null;
		}
		
		getSite().getPage().removePartListener(fPartListener);
		if (fActionGroups != null)
			fActionGroups.dispose();
		super.dispose();
	}
		
	/**
	 * Answer the property defined by key.
	 */
	public Object getAdapter(Class key) {
		if (key == IShowInSource.class) {
			return getShowInSource();
		}
		if (key == IShowInTargetList.class) {
			return new IShowInTargetList() {
				public String[] getShowInTargetIds() {
					return new String[] { JavaUI.ID_PACKAGES, IPageLayout.ID_RES_NAV  };
				}
			};
		}