{quote}We can add the check using the new API if we're building against GTK4. If we're not, we have no way of checking, and this should be closed as out of scope/won't do. {quote} What a check do you want to add? 🤔 The problem is user's code can't init gtk/gdk if Qt already initialized another version. In this example, Qt uses GTK 3 (and it loads GDK 3) and [~jcelerier] loads GDK 2. Closing this as out of scope will just make Qt applications unable to use libraries depending on gtk < 4 and gtk 4 is unlikely to widespread soon. This would be especially a problem for people who support older distributions with one build of app. This problem is unique for Qt since no other toolkit use another toolkit under the hood in a dynamic way.