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/browsing/MembersView.java
*/
	protected String getHelpContextId() {
		return IJavaHelpContextIds.MEMBERS_VIEW;
	}
	/**
	 * Creates the the viewer of this part.
	 * 
	 * @param parent	the parent for the viewer
	 */
	protected StructuredViewer createViewer(Composite parent) {
		ProblemTreeViewer viewer= new ProblemTreeViewer(parent, SWT.MULTI);
		fMemberFilterActionGroup= new MemberFilterActionGroup(viewer, JavaUI.ID_MEMBERS_VIEW);
		return viewer;
	}
	protected void fillToolBar(IToolBarManager tbm) {
		tbm.add(new LexicalSortingAction(getViewer(), JavaUI.ID_MEMBERS_VIEW));
		fMemberFilterActionGroup.contributeToToolBar(tbm);
	}
	
	/**
	 * Answers if the given <code>element</code> is a valid
	 * input for this part.
	 * 
	 * @param 	element	the object to test
	 * @return	<true> if the given element is a valid input
	 */
	protected boolean isValidInput(Object element) {
		if (element instanceof IType) {
			IType type= (IType)element;
			return type.isBinary() || type.getDeclaringType() == null;