I noticed (i.e. I failed to notice months ago) that my screenlock
patch causes rio to redraw the green border. An attempt to
getwindow-and-redraw in the topper proc to fix this is attached, but
fails because screen image r is malloc'd. But I am asking for :130,142
to be merged as

1. it kind of fixes this anyway (as popups never happen in practice), and
2. it's just more efficient.

Further thoughts on screenlock: There's actually no need to discover
the screen size using /dev/screen OR /dev/draw - you can just invoke
newwindow with constants (e.g. 0 0 10000 10000) and rio forces it to
the real screen size. But then you're depending on an unmodded rio
with in principle other window managers could exist.