After a lot of trial and error (and some stupidity because I was not able to revert to a working MSYS2 environment because of no backup) I found the following
I was triggered by this post: GNAT Studio 2026.2 just released! where a GTK problem was solved by setting two GDK envars: GDK_PIXBUF_MODULE_FILE and GDK_PIXBUF_MODULEDIR.
When I set these envars to the GDK-pixbuf folders of the GNATStudio installation, only a warning remained:
(motd.exe:9832): GdkPixbuf-WARNING **: 15:56:58.626: Error loading XPM image loader: Image type “legacy-xpm” is not supported
In the MSYS2 installation a similar file and folder designated by these 2 envvars are also present. However, setting these envars to
/mingw64/lib/gdk-pixbuf-2.0/2.10.0/loaders
resp to
/mingw64/lib/gdk-pixbuf-2.0/2.10.0/loaders.cache
then the critical errors are back and the application hangs.
Note that critical errors don’t happen with a simple hello_world test file, the application must do something with pixbufs, e.g. using the GtkAda.Dialog packages.
Updating the cache via “gdk-pixbuf-query-loaders --update-cache” has no effect (that is what the GNATStudio doinstall for Linux does.)
(Maybe better to close this topic as it more and more appears to be less and less Ada related…)