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
if (itemPart instanceof MDirtyable && ((MDirtyable) itemPart).isDirty()) {
			newName = '*' + newName;
		}
		return newName;
	}
	public Object createWidget(MUIElement element, Object parent) {
		Widget newWidget = null;
		if (!(element instanceof MPartStack) || !(parent instanceof Composite))
			return null;
		Composite parentComposite = (Composite) parent;
		
		
		
		
		int styleModifier = 0; 
		final CTabFolder ctf = new CTabFolder(parentComposite, SWT.BORDER
				| styleModifier);
		
		
		
		ctf.setUnselectedCloseVisible(false);
		newWidget = ctf;
		final IEclipseContext folderContext = getContext(element);
		folderContext.set("canCloseFunc", new IValueFunction() { 
					public Object getValue() {
						return true;
					}
				});
		folderContext.set(FOLDER_DISPOSED, Boolean.FALSE);
		final IEclipseContext toplevelContext = getToplevelContext(element);