Bug 314641 Parts in stacks do not show any content until you switch parts around
bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/workbench/ui/renderers/swt/StackRenderer.java
cti.setControl(ctrl);
		ignoreTabSelChanges = true;
		ctf.setSelection(cti);
		ignoreTabSelChanges = false;
		
		if (ctf.getTopRight() != null) {
			ctf.getTopRight().dispose();
			ctf.setTopRight(null);
		}
		ToolBar tb = getToolbar(element);
		if (tb != null) {
			if (tb.getSize().y > ctf.getTabHeight())
				ctf.setTabHeight(tb.getSize().y);
			
			
			String cssClassName = (String) ctf
					.getData("org.eclipse.e4.ui.css.CssClassName"); 
			stylingEngine.setClassname(tb, cssClassName);
			ctf.setTopRight(tb, SWT.RIGHT);
			ctf.layout(true);
			
			
			
			
			
			
			
			
			
			ctf.notifyListeners(SWT.Resize, null);