Bug 63420 [R21PRES] Flash on tab switch
bundles/org.eclipse.ui.presentations.r21/src/org/eclipse/ui/internal/presentations/R21EditorStackPresentation.java
if (newItem != null) {
					
					if ((e.button == 1) && overImage(newItem, e.x)) {
						getSite().selectPart(getPartForTab(newItem));
						showSystemMenu();
					}
					
					
					CTabItem oldItem = tabFolder.getSelection();
					if (newItem != oldItem)
						return;
				}
				
				if (current != null) {
					current.setFocus();
				}
			}
		}
		/*
		 * (non-Javadoc)
		 * 
		 * @see org.eclipse.swt.events.MouseAdapter#mouseDoubleClick(org.eclipse.swt.events.MouseEvent)
		 */
		public void mouseDoubleClick(MouseEvent e) {
			if (getSite().getState() == IStackPresentationSite.STATE_MAXIMIZED) {
				getSite().setState(IStackPresentationSite.STATE_RESTORED);
			} else {
				getSite().setState(IStackPresentationSite.STATE_MAXIMIZED);
			}
		}