Bug 63420 [R21PRES] Flash on tab switch
bundles/org.eclipse.ui.presentations.r21/src/org/eclipse/ui/internal/presentations/R21EditorStackPresentation.java
getSite().addSystemActions(menuManager);
	}
	/**
	 * Returns the index of the tab for the given part, or returns
	 * tabFolder.getItemCount() if there is no such tab.
	 * 
	 * @param part
	 *            part being searched for
	 * @return the index of the tab for the given part, or the number of tabs if
	 *         there is no such tab
	 */
	private final int indexOf(IPresentablePart part) {
		if (part == null)
			return tabFolder.getItemCount();
		CTabItem[] items = tabFolder.getItems();
		for (int idx = 0; idx < items.length; idx++)
			if (part == getPartForTab(items[idx]))
				return idx;
		return items.length;
	}
	/**
	 * Returns the tab for the given part, or null if there is no such tab
	 * 
	 * @param part
	 *            the part being searched for
	 * @return the tab for the given part, or null if there is no such tab
	 */
	protected final CTabItem getTab(IPresentablePart part) {
		CTabItem[] items = tabFolder.getItems();
		int idx = indexOf(part);