Tests whether the system properties
netbeans.winsys.menu_bar.path, netbeans.winsys.status_line.path
and netbeans.winsys.no_toolbars really do
something.
Represents Popup for "Keyboard document switching" which is shown after
pressing Ctrl+Tab (or alternatively Ctrl+`).
If an user releases a releaseKey in TIME_TO_SHOW ms
the popup won't show at all.
Just a marker (originally,
the method was added due to TabbedHandler.ActivateTopComponentOnMouseClick)
interface for mode GUI component, to be recognized
when traversing AWT hierarchy.