graphics problems with Focal(20) apparently out of date or missing stuff

[Mike Marchywka]

I recently upgraded from Beaver to Focal. That mostly went well 
but there have been a few problems mostly with the graphics
although it looks like in general there may be missed dependencies-
if I install "foo-extra" it may not get "foo-base" although I was
not paying close attention installing the base things solved some problems.

In particular, I was getting consistent segfaults in "FreeFEM" graphics
probrams and vlc failed for a variety of reasons including inability to find
swrast and some other things. I already had the repo mesa but ended
up having to get mesa 20.3.5 as the latest version that looks like it was
easy to build  Are there particular issues with the mesa graphics stuff?

It looks like I'm up now but curious if any of these things are known
issues or I was doing something wrong that is easy to fix.

Thanks. 



 Mike Marchywka 
44 Crosscreek Trail
Jasper GA 30143
was 306 Charles Cox Drive  Canton, GA 30115
470-758-0799
404-788-1216