Re: PGTK-related misconceptions

[Akira Kyle]

On Wed, Jul 27, 2022 at 10:48 AM, Po Lu <luangruo@yahoo.com> 
wrote:

> > Namely gtk behaves differently in stetting GDK_SUPER_MASK on 
> > x11
> > versus wayland where on the former seeing the "Super_R" symbol 
> > will
> > set the mask while on the latter, only the virtual modifier 
> > "Super"
> > will set GDK_SUPER_MASK.
>
> That's because the Wayland compositor isn't sending a keymap 
> that makes
> libxkbcommon assign Mod4 to Super.  See this bit of 
> gdkkeys-wayland.c:
>
>   if (mods & (1 << xkb_keymap_mod_get_index (xkb_keymap, 
>   "Super")))
>     state |= GDK_SUPER_MASK;
>
> which is called from deliver_key_event and 
> keyboard_handle_modifiers in
> gdkdevice-wayland.c:
>
>   seat->key_modifiers = gdk_keymap_get_modifier_state (keymap);
>
> and uses an XKB keymap created in 
> _gdk_wayland_keymap_update_from_fd.
> It is not a bug in GTK, but a bug in the default configuration 
> of the
> Wayland compositor (regardless of what their developers say.)

I'm not totally convinced, since sway should just be using the 
.xkb file I specify. The relevant code is in sway/input/keyboard.c 
where it uses the .xkb file in sway_keyboard_compile_keymap which 
then sway sets using wlr_keyboard_set_keymap inside
sway_keyboard_configure. So this should be the same keymap that 
GTK is using.

Perhaps the bug isn't in GTK but its that mutter is doing 
something special, but I don't immediately see how the function 
add_virtual_mods in src/wayland/meta-wayland-keyboard.c would 
cause this bug and I don't see anything else obviously related to 
this bug.

> > Although it seems like in principle, one should be able to get 
> > xkb to
> > set the "Super" virtual modifier so that GTK correctly picks it 
> > up in
> > it's wayland code. However thus far I have been unable to make 
> > a set
> > of xkb rules which will trigger the "Super" virtual modifier 
> > for the
> > <RWIN> keycode despite much effort. Perhaps this is possible 
> > and I
> > just don't understand xkb's rules sufficiently, or perhaps 
> > there is
> > some issue in xkb which is preventing from GTK to picking up 
> > the
> > "Super" virtual modifier. Thus far I have tried many variations 
> > on
>
> Could you please send the entire XKB file generated?  Thanks.

Attached.

dvorak_super_compiled.xkb
Description: Text document