Bug 63420 [R21PRES] Flash on tab switch
bundles/org.eclipse.ui.presentations.r21/src/org/eclipse/ui/internal/presentations/R21BasicStackPresentation.java
private final int indexOf(IPresentablePart part) {
		if (part == null) {
			return paneFolder.getItemCount();
		}
		CTabItem[] items = paneFolder.getItems();
		for (int idx = 0; idx < items.length; idx++) {
			IPresentablePart tabPart = getPartForTab(items[idx]);
			if (part == tabPart) {
				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 = paneFolder.getItems();
		int idx = indexOf(part);
		if (idx < items.length) {
			return items[idx];
		}
		return null;
	}
	/**
	 * @param part