Bug 22573 Can't make OK to appear in type hierarchy history dialog [type hierarchy]
Build 20020813 1. Open Type Hierarchy (1st time). 2. Click on the history toolbar button 3. Press "Remove" on the dialog ==> no way to enable "OK" It would be better not to allow to remove the actual type hierarchy.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/typehierarchy/HistoryListAction.java
fHistoryList.setElements(Arrays.asList(elements));
			
			ISelection sel;
			if (elements.length > 0) {
				sel= new StructuredSelection(elements[0]);
			} else {
				sel= new StructuredSelection();
			}
			
			fHistoryList.selectElements(sel);
		}
		
		/*
		 * @see Dialog#createDialogArea(Composite)
		 */
		protected Control createDialogArea(Composite parent) {
			initializeDialogUnits(parent);
			
			Composite composite= (Composite) super.createDialogArea(parent);
			
			Composite inner= new Composite(composite, SWT.NONE);
			inner.setLayoutData(new GridData(GridData.FILL));
			LayoutUtil.doDefaultLayout(inner, new DialogField[] { fHistoryList }, true, 0, 0);
			LayoutUtil.setHeigthHint(fHistoryList.getListControl(null), convertHeightInCharsToPixels(12));
			LayoutUtil.setHorizontalGrabbing(fHistoryList.getListControl(null));
				
			fHistoryList.getTableViewer().addDoubleClickListener(new IDoubleClickListener() {
				public void doubleClick(DoubleClickEvent event) {
					if (fHistoryStatus.isOK()) {
						okPressed();