Bug 25827 Disposing of MemberFilterActionGroup
Build 2.0.2 and 2.1 When investigating an editor memory leak PR we found out that this group has a dispose method which is never called. When we then called from the editor it throw an exeption (viewer was disposed). Don't know if the group really needs dispose() if so it should get called.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/PackageExplorerActionGroup.java
type == IJavaElement.COMPILATION_UNIT ||
			type == IJavaElement.TYPE;
	}
	
	private boolean isGoIntoTarget(Object element) {
		if (element == null)
			return false;
		if (element instanceof IJavaElement) {
			int type= ((IJavaElement)element).getElementType();
			return type == IJavaElement.JAVA_PROJECT || 
				type == IJavaElement.PACKAGE_FRAGMENT_ROOT || 
				type == IJavaElement.PACKAGE_FRAGMENT;
		}
		return false;
	}
	private void addOpenNewWindowAction(IMenuManager menu, Object element) {
		if (element instanceof IJavaElement) {
			element= ((IJavaElement)element).getResource();
			
		}
		if (!(element instanceof IContainer))
			return;
		menu.appendToGroup(
			IContextMenuConstants.GROUP_OPEN, 
			new OpenInNewWindowAction(fPart.getSite().getWorkbenchWindow(), (IContainer)element));
	}
	
	 void handleDoubleClick(DoubleClickEvent event) {
		TreeViewer viewer= fPart.getViewer();
		Object element= ((IStructuredSelection)event.getSelection()).getFirstElement();