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
index++;
		}
		return index;
	}
	@Override
	public void childRendered(
			final MElementContainer<MUIElement> parentElement,
			MUIElement element) {
		super.childRendered(parentElement, element);
		if (!(((MUIElement) parentElement) instanceof MPartStack)
				|| !(element instanceof MPart))
			return;
		showChild(parentElement, element);
		
		
		Control ctrl = (Control) element.getWidget();
		if (ctrl != null) {
			
			stylingEngine.style(ctrl);
		}
	}
	private CTabItem findItemForPart(MElementContainer<MUIElement> stack,
			MUIElement part) {
		CTabFolder ctf = (CTabFolder) stack.getWidget();
		if (ctf == null)
			return null;
		CTabItem[] items = ctf.getItems();
		for (int i = 0; i < items.length; i++) {
			if (items[i].getData(OWNING_ME) == part)
				return items[i];