Hey there.. Not sure if I should post here or a separate thread... I finally completely uninstalled sguyader's last build which got rid of the issue I posted about above with the 'no disk in drive' messages with your x64 builds. (Deleting my modified options file seemed to do the trick. I tried having them coexist side by side but still had the problem.)
Now I have noticed a new issue with your 'release_gtk3-bugfix_4.2.1412' build. It does not allow me to change the theme and only allows the 'RawTherapee' theme. I installed and ran the 'debug_gtk3-bugfix_4.2.1412' build as well but don't know what I need to do to report this bug properly.
I've also installed your latest 'locallab_4.2.1265' and 'pixelshift_4.2.1241' and these two builds do not have the issue with the theme selection. In fact, I discovered that these have other themes I had not seen before and I really like them which makes me want to see the issue in gtk3 4.2.1412 resolved even more.
So I will do whatever you ask of me if it can help.
Fwiw, I also just installed 'release_gtk3-bugfix_4.2.1409' and it also has the same problem as 1412. This is all on Windows 10...