Global Shortcut support on Wayland

[wusyong]

Global Shortcut on Linux only works on x11 because wayland-protocols hasn't define anything yet.
There's a RFC about this.
While we can use some workaround or implement one our own, it won't be supported by all DEs.
We'll have to wait wayland decide to add this.

[Pajn]

There is now a desktop portal for this flatpak/xdg-desktop-portal#711

Draft implementation in KDE:
https://invent.kde.org/plasma/xdg-desktop-portal-kde/-/merge_requests/80
https://invent.kde.org/libraries/xdg-portal-test-kde/-/merge_requests/6

Gnome and wlroots only have tracking issues atm:
https://gitlab.gnome.org/GNOME/xdg-desktop-portal-gnome/-/issues/47
emersion/xdg-desktop-portal-wlr#240

[ShellWen]

org.freedesktop.portal.GlobalShortcuts has gained widespread support; all that is needed is for someone to write the D-Bus communication.

[Exidex]

I have looked into implementing this with intention to upstream it but, unfortunately, it doesn't seem like a good idea to implement org.freedesktop.portal.GlobalShortcuts in this crate. At least not without public API overhaul.

Here's how GlobalShortcuts portal works:

• you can bind a shortcut by providing a shortcut id string and a description of said shortcut that will be visible to the user in a system settings window. you can also optionally provide default modifiers+key
• you cannot unbind said shortcut
• you can get a list of previously bound shortcuts
• you can listen on "activation" event (shortcut is pressed, event is repeated if shortcut is held) and "deactivation" event (shortcut is released)
  • this event contains shortcut id and timestamp among other things
• and you can listen on "shortcut changed" event which will be sent if user changes shortcut in system settings window

Taking all this into account, for application developers, I think, it would be more reasonable to implement global shortcuts for wayland using separate crate like ashpd given how big the difference in API is