Bug 303549 [UI] Dragging the last element from a stack causes placeholders to appear
The check to 'pick' a new element to select isn't checking whether the 'toBeRendered' is true.
bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/workbench/ui/renderers/swt/StackRenderer.java
}
	@Override
	public void hookControllerLogic(final MUIElement me) {
		super.hookControllerLogic(me);
		if (!(me instanceof MElementContainer<?>))
			return;
		final MElementContainer<MUIElement> stack = (MElementContainer<MUIElement>) me;
		
		CTabFolder ctf = (CTabFolder) me.getWidget();
		ctf.addSelectionListener(new SelectionListener() {
			public void widgetDefaultSelected(SelectionEvent e) {
			}
			public void widgetSelected(SelectionEvent e) {
				MPart newPart = (MPart) e.item.getData(OWNING_ME);
				if (stack.getSelectedElement() != newPart) {
					activate(newPart);
				}
				showTab(stack, newPart);
			}
		});
		CTabFolder2Adapter closeListener = new CTabFolder2Adapter() {
			public void close(CTabFolderEvent event) {
				MPart part = (MPart) event.item
						.getData(AbstractPartRenderer.OWNING_ME);
				
				IEclipseContext partContext = part.getContext();
				IValueFunction closeFunc = (IValueFunction) partContext
						.get("canCloseFunc"); 
				boolean canClose = closeFunc == null
						|| (Boolean) closeFunc.getValue();