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
if (otherItem instanceof MPart)
					otherPart = (MPart) otherItem;
			}
			if (otherPart == null)
				continue;
			if (skipThisPart && part.equals(otherPart))
				continue; 
			if (otherPart.isToBeRendered())
				others.add(otherPart);
		}
		EPartService partService = getContextForParent(part).get(
				EPartService.class);
		for (MPart otherPart : others) {
			if (partService.savePart(otherPart, true))
				partService.hidePart(otherPart);
		}
	}
	private MMenu getViewMenu(MPart part) {
		if (part.getMenus() == null) {
			return null;
		}
		for (MMenu menu : part.getMenus()) {
			if (menu.getTags().contains(TAG_VIEW_MENU)) {
				return menu;
			}
		}
		return null;
	}
}