At top 46px the button lay in the empty end of Big Picture's filter area, but that bar is a
positioned layer (z-index 55) painted over the button (z-index 20): nothing opened on click (rega,
1440, en and ar). The filter area wraps with width, so no spot below it is free at every width (at
1024 the stats row moves under a fixed offset). pos.raise lifts the BUTTON to z-index 60; the one-time
pointer stays under the bar, so no filter is covered even visually. Measured on the built tree: no
interactive element or text under the button, the button topmost at its centre, and a click opens the
popup, at 1440, 1024 and 800, en and ar.