Regarding VLC, i found this post from 2006:https://ubuntuforums.org/showthread.php?t=316155
( i was too lazy to read it all ).
About pgAdmin, apparently they had some stability problems and blamed wxWidgets, but i don't know if this was the main reason. viewtopic.php?t=40030
In general and today, wxWidgets' downsides are:
- no mobile support
- native controls.
This is a big plus for many wxWidgets users, including me. But it also makes skinning an application very hard and a lot of effort. If that's important for you (like VLC), wxWidgets is not the right tool for the job
- small(er) user base. Especially open source projects depend on the collaboration of many developers and there aren't just that many wxWidgets developers around. When comparing to web technologies, i would estimate a ratio of 5000 : 1, maybe even more