Re: PGTK-related misconceptions

[Akira Kyle <akira@akirakyle.com>]

On Tue, Jul 26, 2022 at 10:08 AM, Po Lu <luangruo@yahoo.com> 
wrote:

> It is to prevent errors when Mod4 is _not_ the super key.  Very 
> common
> on X (where Mod4 is commonly Hyper), and in fact it is caused by 
> Mod4
> not being part of the Super virtual modifier in the compositor's 
> XKB
> configuration.
>
> The conclusion I eventually came to is that the problem lies in 
> the XKB
> configuration of the Wayland compositor in question (namely, 
> Sway), and
> not Emacs nor GDK.  It works with GNOME Shell and kwin because 
> they set
> up their keyboards with the correct virtual modifiers by 
> default.  So
> what I'd recommend is to start an X server where the Super key 
> does
> work, run:
>
>   xkbcomp $DISPLAY name/of/xkb/file.xkb
>
> and then use that file with Sway.

This does not appear to work. I can attach the full .xkb file that 
xkbcomp generated if you like, but it's the default which you get 
from the following under the v2.34 xkeyboad-config files.

xkb_keymap "my_dvorak_super" {
    xkb_keycodes        { include "evdev" };
    xkb_compatibility   { include "complete" };
    xkb_types           { include "complete" };
    xkb_symbols         { include "us(dvorak)+pc(pc105)" };
};

Specifically, when I use the same .xkb file under X I get that 
emacs interprets the physical keycode <RWIN> as Super whereas 
under wayland with sway, emacs does not respond to <RWIN>. The 
relevant lines from the xkb_symbols section are

    key <RWIN> {         [         Super_R ] };
    modifier_map Mod4 { <RWIN> };

Reading through the links that Trey sent in previous emails to the 
gtk source which handles modifier keys in x11 versus wayland, I'm 
pretty convinced his diagnosis is correct. 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.

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 some configuration like the following

default partial modifier_keys xkb_symbols "basic" {
    include "us(dvorak)"
    name[Group1] = "super";
    key <RWIN>  {
        symbols[Group1]= [ Super_R ],
        virtualMods= Super
        };
    key <LWIN>  {
        symbols[Group1]= [ Super_L ],
        virtualMods= Super
        };
};

What is also puzzling to me is that my .xkb file also includes the 
"misc" xkb_compatibility rules which look like the following

    interpret Super_R+Any {
	virtualModifier= Super;
	action = SetMods(modifiers=modMapMods);
    };

    interpret Super_R {
	action = SetMods(modifiers=Super);
    };