Bug 67513 [R21PRES] view tab tool tip inconsistent with 2.1
In 2.1, the tab item tool tip appeared in the stack's title bar, not on the tab item itself. The r21presentation currently puts the tip on the tab item. I'll attach a patch that fixes the problem.
bundles/org.eclipse.ui.presentations.r21/src/org/eclipse/ui/internal/presentations/R21BasicStackPresentation.java
public void setActive(boolean isActive) {
		activeState = isActive;
		updateGradient();
	}
	/**
	 * Return whether the window's shell is activated
	 */
	boolean getShellActivated() {
		return shellActive;
	}
	/**
	 * Returns the top level window.
	 */
	public Window getWindow() {
		Control ctrl = getControl();
		if (ctrl != null) {
			Object data = ctrl.getShell().getData();
			if (data instanceof Window)
				return (Window) data;
		}
		return null;
	}
	private CTabItem createPartTab(IPresentablePart part, int tabIndex) {
		CTabItem tabItem;
		int style = SWT.NONE;
		if (getSite().isCloseable(part))
			style |= SWT.CLOSE;
		tabItem = paneFolder.createItem(style, tabIndex);
		tabItem.setData(TAB_DATA, part);
		part.addPropertyListener(childPropertyChangeListener);