Errors of an old GUI library

I am collaborating in documenting a GUI library for the Harbour programming language. When running the program from a window containing a button bar, it does not work. It uses gtk±2.0. I don’t know about GTK, but if you give me some hints I could look into sharing it with some colleagues.
Thank you very much.

Antonio F.S.

Please, don’t use screenshots for error messages: the text is cut, so we can’t see what’s happening.

Additionally, GTK 2.x is EOL, so there’s really no community support for it any more.

From the fragment of message, it seems you’re violating the preconditions on a series of functions. This is a programmer error.

My personal suggestion is to use a debugger like GDB and export G_DEBUG=fatal-criticals in your environment; then GTK will abort at the first critical warning, and will allow you to see the backtrace that led to the assertion failure.

I’m sorry. I didn’t know that. I also have little experience with this type of forum. Please excuse me.

Thank you very much for your contribution.

Best regards.
Antonio F.S.