windows would vanish at times (eg dnd into an empty desktop in the
pager). this was pretty disconcerting and a problem, so this fixes it
with a bit of a sledgehammer, but it fixes it.
@fix
* finish updating for E19 api
* fix visibility changing on sources
** use that shelf data item added in previous commit to detect shelf visibility
* fix sizing (but not scaling :() and positioning of sources
* also fix stacking
Carsten Haitzler
Chris Michael
Mike Blumenkrantz
Mike Blumenkrantz