GtkCanvas and Testset Error

[nHackel]

Hello, we stumbled over an issue with our UI tests after migrating to Gtk4.jl. In the tests we are creating a complex GUI that features multiple GtkCanvases, which we then compare to expected images. With Gtk4.jl these tests fail with the Canvas not being initialized.

I've managed to reduce it to this MWE:

using Gtk4, Test

@testset begin
	c = GtkCanvas()
	win = GtkWindow(c)
	# show(win) # doesn't work with or without show
	getgc(c)
end

I think the tests within Gtk4.jl works somewhat similar (at least they create Canvases within a testset), I'm not sure exactly what I'm missing to get this to work

[jwahlstrand]

I won't have time to look into this until the weekend, but you could also look at GtkObservables and ImageView, which use GtkCanvas heavily and have extensive tests. I think you need to call sleep. If I recall correctly, recently I had to add more sleep because CI was behaving differently on Mac OS.

[jwahlstrand]

Adding sleep(1.0) just before the getgc call fixes it for me.