Bug 48452 Widget is disposed while closing cool bar
This is the problem that is occurring in the nightly builds. There is something happening where a cool bar is attempting to layout disposed cool bar items.
bundles/org.eclipse.jface/src/org/eclipse/jface/action/ToolBarContributionItem.java
if ((parentMenu != null) && (!parentMenu.isDisposed())) {
			toolBar.setMenu(parentMenu);
			
			parentMenu.addListener(SWT.Hide, new Listener(){
				public void handleEvent(Event event) {
					ToolBar toolBar = toolBarManager.getControl();
					if (toolBar != null) {
						toolBar.setMenu(null);
						Menu parentMenu = toolBar.getParent().getMenu();
						if (parentMenu != null) {
							parentMenu.removeListener(SWT.Hide,this);
						}
					}
				}
			});
		}
	}
	
	/**
	 * Handles the disposal of the widget.
	 * @param event the event object
	 */
	private void handleWidgetDispose(DisposeEvent event) {
		coolItem = null;	
	}
	
	
	/* (non-Javadoc)
	 * @see org.eclipse.jface.action.IContributionItem#saveWidgetState()
	 */