I'm just trying to get gtk working on raspberry pi os. Everything compiles and builds but like you I get same error message when running code. when this line executes: gtk_window_new(GTK_WINDOW_TOPLEVEL);

I'd be really grateful if you could elaborate on your answer a little. I don't know an XPM is and google is coming up with real estate proteries lol. Also, could you show what you canged in your code or build settings please.