combo-field% glitch in Linux

[James Platt]

I'm seeing a glitch with all Racket combo fields when run in Linux Mint 19.3. When you click on the popup menu, it just flashes open for an instant and then disappears, the first item becomes selected without actually clicking on it with the mouse, and the callback is triggered. If you hold the mouse button down rather than just clicking, then you are able to make a selection. However, this isn't intuitive to a typical user. Running a simple example, like below, gives the error shown below when run from Terminal. I don't see the error message in DrRacket but the problem is the same. The glitch does not occur in macOS. I'm guessing that this is a GTK bug rather than a Racket bug but that's just a guess. Is there something that can be done in Racket or is this something that needs to be fixed in Linux?


Error message:
(Combo-select-test.rkt:2195): Gtk-WARNING **: 12:02:54.443: no trigger event for menu popup


#lang racket

(require racket/gui)

(define frame (new frame%
[label "Combo Field Test"]
))


(new combo-field% (parent frame)
(label "choose")
(choices '("choice1" "choice2" "choice3"))
(callback (lambda (c e) (println "A choice was made.")))
)

(send frame show #t)