Bug 63420 [R21PRES] Flash on tab switch
bundles/org.eclipse.ui.presentations.r21/src/org/eclipse/ui/internal/presentations/R21EditorStackPresentation.java
}
	/**
	 * Adds the given presentable part to this presentation at the given index.
	 * Does nothing if a tab already exists for the given part.
	 * 
	 * @param newPart
	 * @param index
	 */
	public void addPart(IPresentablePart newPart, int index) {
		
		if (getTab(newPart) != null) {
			return;
		}
		createPartTab(newPart, index);
		
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.ui.internal.skins.StackPresentation#removePart(org.eclipse.ui.internal.skins.IPresentablePart)
	 */
	public void removePart(IPresentablePart oldPart) {
		if (current == oldPart)
			current = null;
		CTabItem item = getTab(oldPart);
		if (item == null) {
			return;
		}
		oldPart.setVisible(false);
		item.dispose();