Bug 239300 [TabbedProperties] underline missing from tab label when tab has focus
bundles/org.eclipse.ui.views.properties.tabbed/src/org/eclipse/ui/internal/views/properties/tabbed/view/TabbedPropertyList.java
/**
	 * Based on available space, figure out the top and bottom tabs in the list.
	 */
	private void computeTopAndBottomTab() {
		computeTabsThatFitInComposite();
		if (elements.length == 0) {
			/*
			 * no tabs to display.
			 */
			topVisibleIndex = 0;
			bottomVisibleIndex = 0;
		} else if (tabsThatFitInComposite >= elements.length) {
			/*
			 * all the tabs fit.
			 */
			topVisibleIndex = 0;
			bottomVisibleIndex = elements.length - 1;
		} else if (getSelectionIndex() == NONE) {
			/*
			 * there is no selected tab yet, assume that tab one would
			 * be selected for now.
			 */
			topVisibleIndex = 0;
			bottomVisibleIndex = tabsThatFitInComposite - 1;
		} else if (getSelectionIndex() + tabsThatFitInComposite > elements.length) {
			/*
			 * the selected tab is near the bottom.
			 */
			bottomVisibleIndex = elements.length - 1;
			topVisibleIndex = bottomVisibleIndex - tabsThatFitInComposite + 1;