Status items are the things on the right end of the Mac menu bar, like the
clock and volume widget.  It turns out that they are displayed at a higher
window level than everything else in the menu bar.  For the case where the
displays are not captured for a full-screen window, the window ends up at the
same window level as the status items, and they would sometimes end up on top.
They would draw over the full-screen window and could be clicked.