Bug 328296 DND of markers views causes NPE in StackRenderer
bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/ui/workbench/renderers/swt/StackRenderer.java
ctf.addListener(SWT.Activate, new org.eclipse.swt.widgets.Listener() {
			public void handleEvent(org.eclipse.swt.widgets.Event event) {
				CTabFolder ctf = (CTabFolder) event.widget;
				MElementContainer<MUIElement> stack = (MElementContainer<MUIElement>) ctf
						.getData(OWNING_ME);
				activateStack(stack);
			}
		});
	}
	private boolean closePart(Widget widget) {
		MUIElement uiElement = (MUIElement) widget
				.getData(AbstractPartRenderer.OWNING_ME);
		MPart part = (MPart) ((uiElement instanceof MPart) ? uiElement
				: ((MPlaceholder) uiElement).getRef());
		IEclipseContext partContext = part.getContext();
		IEclipseContext parentContext = getContextForParent(part);
		
		IEclipseContext context = partContext == null ? parentContext
				: partContext;
		
		EPartService partService = (EPartService) context
				.get(EPartService.class.getName());
		if (partService.savePart(part, true)) {
			partService.hidePart(part);
			return true;
		}
		
		
		return false;
	}