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
int minimumWidth = toolItemWidth * getMinimumItemsToShow();
			coolItem.setMinimumSize(minimumWidth, toolBarSize.y);
		}else {
			coolItem.setMinimumSize(toolBarSize.x, toolBarSize.y);
		}
		
		if (changeCurrentSize) {
			
			coolItem.setSize(prefferedSize);
		}
	}
	
	/**
	 * Create and display the chevron menu.
	 */
	private void handleChevron(SelectionEvent event) {
		CoolItem item = (CoolItem) event.widget;
		Control control = item.getControl();
		if ((control instanceof ToolBar) == false) {
			return;
		}
		CoolBar coolBar = item.getParent();
		Point chevronPosition = coolBar.toDisplay(new Point(event.x, event.y));
		ToolBar toolBar = (ToolBar) control;
		ToolItem[] tools = toolBar.getItems();
		int toolCount = tools.length;
		int visibleItemCount = 0;
		while (visibleItemCount < toolCount) {
			Rectangle toolBounds = tools[visibleItemCount].getBounds();
			Point point = toolBar.toDisplay(new Point(toolBounds.x, toolBounds.y));