Windows dont move correctly with "non standard" screen scales.

[MichaelSchloesser]

Windows 10 (and other OS as well) allows the user to set a scale parameter, that changes the size of text, apps and some other things. This is useful when using a device with high resolution but small display (in this case a microsoft surface). However when i create a window using Mousetrap, and try to drag it somewhere, this scale parameter does not seem to be taken into account. Suppose i use a scale of 200% and want to drag the window to a position (x, y) then it ends up at (2x, 2y) instead.

I was not able to reproduce this on any other Windows machine.

Device specifications:
Device name: Microsoft-Surface
Processor: Intel(R) Core(TM) i5-1035G4 CPU @ 1.10GHz 1.50 GHz
Installed RAM: 8,00 GB (7,60 GB usable)
System type: 64-bit operating system, x64-based processor
Pen and touch: Pen and touch support with 10 touch points

Windows specifications:
Edition: Windows 10 Home
Version: 22H2
Installed on: ‎ 20/‎01/‎2023
OS build: 19045.3930
Experience: Windows Feature Experience Pack 1000.19053.1000.0

[Clemapfel]

Hi, I think this is fixable but I need to research how to make the back-end aware of the monitor scale. I'll ask my GNOME contacts, which may take a few days, and get back to you.

Until then, could you run

begin
    using Mousetrap
    gtk4 = Mousetrap.detail.GTK4_jll.libgtk4
    gio = Mousetrap.detail.Glib_jll.libgio

    widget = Separator()
    widget_ptr = Mousetrap.as_gobject_pointer(widget)
    gtk_display = @ccall gtk4.gtk_widget_get_display(widget_ptr::Ptr{Cvoid})::Ptr{Cvoid}
    gtk_monitor_list = @ccall gtk4.gdk_display_get_monitors(gtk_display::Ptr{Cvoid})::Ptr{Cvoid}
    gtk_monitor = @ccall gio.g_list_model_get_item(gtk_monitor_list::Ptr{Cvoid}, 0::Int)::Ptr{Cvoid}
    println("Monitor Scale: ", @ccall gtk4.gdk_monitor_get_scale_factor(gtk_monitor::Ptr{Cvoid})::Int)
end

in the REPL and tell me what it prints?

[MichaelSchloesser]

Hi, thanks for your quick answer.

running your code get the following error (on both my surface and my desktop computer):

ERROR: UndefVarError: as_gobject_pointer not defined
Stacktrace:
 [1] getproperty(x::Module, f::Symbol)
   @ Base .\Base.jl:31
 [2] top-level scope
   @ .\REPL[2]:7

[Clemapfel]

Sorry for the period of inactivity, I found out this was an issue fixed with GTK4.12: https://gitlab.gnome.org/GNOME/gtk/-/issues/5877, so it was a bug. This will be fixed when the binary builder jll package mousetrap depends on is updated.