while writing this email I found a solution to my problem.
By setting the PLT_GTK2 environment variable to:
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
Here is the program:
(define frame (new frame% [label "Bug: crashing scrollbars"]))
(define box (new list-box%
[choices (list "A" "B")]
(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
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