Mouse scroll does not trigger callback while SHIFT modifier is used

[kschertler]

Currently only noticed on the Mac, the following code does not call the sig_scroll callback (see below) while the SHIFT modifier is pressed. Other modifiers correctly do produce the expected @show output.

using GtkObservables
using GtkObservables.Gtk4

win = GtkWindow("Test")
c = canvas()
push!(win, c)

sig_scroll = on(c.mouse.scroll) do scroll
    @show scroll
end

The problem seems to be related to the use of an external mouse, since using a two-finger gesture on the touchpad of the Mac (to do the scrolling) works correctly.

I'm using the following system (but same problem exists on Julia 1.9):

versioninfo()
Julia Version 1.8.4
Commit 00177ebc4fc (2022-12-23 21:32 UTC)
Platform Info:
  OS: macOS (x86_64-apple-darwin21.4.0)
  CPU: 8 × Intel(R) Core(TM) i7-8559U CPU @ 2.70GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-13.0.1 (ORCJIT, skylake)
  Threads: 8 on 8 virtual cores

GtkObservables v2.0.1

[kschertler]

The issue has been confirmed on an independent system here:

#57 (comment)