Bug#977693: gtk+3.0: Wayland primary selection interoperability with GTK clients on Plasma Desktop

[Simon McVittie]

Control: found -1 3.24.23-3
Control: notfound -1 3.24.24-1
Control: tags -1 + moreinfo

On Sat, 19 Dec 2020 at 02:06:49 +0100, Sandro Knauß wrote:
> currently it is impossible to use middle click pasting between Wayland 
> clients and GTK clients running on XWayland, like for example Chromium 
> and Firefox on Plasma Desktop.

Are you sure this isn't already present in testing and unstable's
libgtk-3-0? The primary-selection-unstable-v1 protocol was mentioned in
the upstream NEWS file for 3.24.24.

> Upstream GTK developer Emmanuele Bassi said that there are no more gtk3 
> dot releases planned (at least not before GTK 4.0 is released). 

That seems to be outdated information: GTK 4.0.0 has been released now
(I uploaded it to experimental NEW since it has a new SONAME and needs
a newer version of Pango), and a 3.24.24 point release also happened.

> Emmanuale recommends cherry-picking this patch from the gtk-3-24 stable 
> branch to distro packages:
> 
> https://gitlab.gnome.org/GNOME/gtk/-/commit/9a693c7228a88b76a007aed41b101d89d084cf9b

That's included in 3.24.24, in testing since 2020-12-14.

> To verify that the patch works:
> 1. Log into a Plasma Wayland session

I'll try to test this at some point, but it's very likely to be quicker
for a Plasma user to upgrade their GTK 3 version than it is for me to
install Plasma.

This is not a fully interoperable protocol until it's declared stable
by the Wayland developers, and the stable version is implemented by GTK,
Plasma, GNOME Shell, and any other relevant toolkits such as Qt. However,
it seems to be very similar to the older GTK-specific primary selection
interface (perhaps identical except for changing the names), so hopefully
having the GTK version, the standardized unstable version and a future
standardized stable version all exist in parallel for a few months/years
won't be a significant maintenance burden for the various projects
involved.

It would probably be pragmatic for Plasma to implement the GTK-specific
interface too, at least for a while, if they're as similar as they seem
to be from the GTK change - that would make sure it interoperates with
older GTK versions, for instance in Flatpak/Snap apps that are stuck on
an older runtime, apps from a Debian 10 chroot, or the Debian-10-based
Steam Runtime.

    smcv