absolute positioning and other "missing features" of Wayland

[cycl0ps at tuta.io]

Hi Dima,

Thank you for your correspondence on this. According to the previous           
announcement [0] good progress was made towards using a heuristic on popup     
windows to position them as subsurfaces, that seems like what Wine users would 
probably want to use in most cases because it preserves client isolation. Is   
anyone keeping track of a list of applications where this doesn't work? A set  
of test cases would be best here. It looks like additional compositor support  
would be needed only for applications where a heuristic absolutely doesn't work
at all. I wouldn't say it's "evil" or "undesirable" to have something else a   
compositor can do there, but it probably would be wanted only as a last resort
for the odd application that cannot be made to work securely.

Thanks,
- Jason

[0]: https://www.winehq.org/pipermail/wine-devel/2020-December/178575.html