Give console's overlay a high z only in select mode, since in this case
you want to click it so it should be above other overlays. In particular
console should be above the OSC's box layout with visibility=always when
you show it by clicking its buttons.
Keep using z=0 otherwise when it doesn't handle clicks, to avoid
unintuitive behavior of overlays handling clicks like the OSC being
drawn below console.
Since the legacy mp.set_osd_ass() doesn't accept z, we need to repeat
its caching logic, like 490b3ba007 and 86d24b069b did for the OSC.
Guido Cella
effa81eb6e