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
if (val != null) {
			fLinkingEnabled= val.intValue() != 0;
		}
	}
	
	
	/**
	 * view part becomes visible
	 */
	protected void visibilityChanged(boolean isVisible) {
		fIsVisible= isVisible;
		if (isVisible && fNeedRefresh) {
			doTypeHierarchyChanged(fHierarchyLifeCycle, null);
		}
		fNeedRefresh= false;
	}
	
	
	/**
	 * Link selection to active editor.
	 */
	protected void editorActivated(IEditorPart editor) {
		if (!isLinkingEnabled()) {
			return;
		}
		if (fInputElement == null) {
			
			return;
		}