private void updateButton(MouseEvent event)
		{
			int index = getUI().tabForCoordinate(CloseableTabbedPane.this, event.getX(), event.getY());
			if (index != -1 && index != getSelectedIndex()) {
				if (visibleIndex == index) {
					return;
				}
				setButtonVisible(index, true);
				if (visibleIndex != index && visibleIndex != -1 && visibleIndex != getSelectedIndex()) {
					setButtonVisible(visibleIndex, false);
				}
				visibleIndex = index;
			} else if (visibleIndex != -1 && visibleIndex != getSelectedIndex() && visibleIndex < getTabCount()) {
				setButtonVisible(visibleIndex, false);
				visibleIndex = -1;
			}
		}