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
activate(selPart);
		}
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * org.eclipse.e4.workbench.ui.renderers.swt.LazyStackFactory#internalChildAdded
	 * (org.eclipse.e4.ui.model.application.MPart,
	 * org.eclipse.e4.ui.model.application.MPart)
	 */
	@Override
	protected void showChild(MElementContainer<MUIElement> stack,
			MUIElement part) {
		
		super.showChild(stack, part);
		MUILabel itemPart = (MUILabel) part;
		CTabFolder ctf = (CTabFolder) stack.getWidget();
		int createFlags = 0;
		CTabItem cti = findItemForPart(stack, part);
		if (cti == null) {
			int index = calcIndexFor(stack, part);
			
			
			cti = new CTabItem(ctf, createFlags, index);
			cti.setData(OWNING_ME, part);
			cti.setText(getLabel(itemPart, itemPart.getLabel()));
			cti.setImage(getImage(itemPart));
			cti.setToolTipText(itemPart.getTooltip());
			Control ctrl = (Control) part.getWidget();