Hello, while writing this email I found a solution to my problem. By setting the PLT_GTK2 environment variable to: export PLT_GTK2=/usr/lib64/libgtk-x11-2.0.so like described in https://docs.racket-lang.org/gui/libs.html The program runs with gtk2 and no longer crashes (with gtk3 it does for me)
This seems to indicate that this is gtk3 bug. Below my original question. I have a short gui program which crashes when I move my cursor over the list box and then leave its area while passing the scrollbar. I am not sure whether this is a gtk or racket bug. I am running Manjaro 17.1 with Xfce 4.12 and Racket v6.12 Someone on irc tried it and could not reproduce it with Xfce 4.12 and Racket v6.12. Here is the program: #lang racket (require racket/gui) (module+ main (define frame (new frame% [label "Bug: crashing scrollbars"])) (define box (new list-box% [label #f] [choices (list "A" "B")] [parent frame])) (send frame show #t)) ;; after leaving the list-box hovering over the scrollbar with the mouse: ;; Gtk: _gtk_css_image_get_concrete_Thank you size: assertion 'default_width > 0' failed ;; Gtk: _gtk_css_image_get_surface: assertion 'surface_width > 0' failed ;; SIGSEGV MAPERR si_code 1 fault on addr 0x1c ;;  4105 abort (core dumped) racket gtkbug.rkt -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.