No middle-click on GNOME app title bar in KDE

[Francois Gouget]

So I have configured KDE to send a window to the background when I
middle click in its title bar [1]. But when I do on the 'title bar' of a
GNOME application (e.g. Gedit) nothing happens. [2]

My understanding is that this is because GNOME applications don't have a
window manager-controlled title bar. Instead they have an
application-controlled "header bar" with a hardcoded behavior that does
not match the KDE configuration. [3]

BUT...

A right-click in the "header bars" brings up a different menu depending
on whether the GNOME application is running in GNOME or in KDE. So they
are somehow aware of the environment they are in and appear to be able
to adapt to it.

The content of the right-click menu still does not match the one I get
when right-clicking on a real title bar.

So on the one hand GNOME header bars seem to be able to adapt to the
desktop environment they are in, but on the other hand they still don't
match it.

Is it because I misconfigured something? Is there a special package that
needs to be installed to let GNOME applications better integrate with
KDE?

SO...

Do I have discrepencies because KDE never provided the required support?
Or is it that GNOME applications lack the support for integrating with
any environment besides GNOME? (and revert to a hardcoded default
behavior in such cases)



[1] System Settings -> Window Management -> Window Behavior -> Titlebar
actions -> Titlebar and Frame Actions -> Middle click -> Lower.

[2] In GNOME a middle-click on a GNOME header bar is treated as a
left-click, that is it raises the window. But the same action on a
GNOME header bar in KDE gives focus the first time, and raises it
the second time. So if the window is already raised and has the
focus nothing happens.

[3] In fact one can configure Mutter so a middle-click lowers the
window:
gsettings set org.gnome.desktop.wm.preferences \
action-middle-click-titlebar 'lower'
(set to 'none' for the default behavior)
But this only works on real window manager-controlled title bars. So
it works on KDE's Konsole for instance, but not on GNOME's own GNOME
Terminal or Gedit!

--
Francois Gouget <fgo...@free.fr> http://fgouget.free.fr/
You don't liberate a people. A people liberates itself.
Youssoupha

[Curt]

On 2022-07-26, Francois Gouget <fgo...@free.fr> wrote:
>
> So I have configured KDE to send a window to the background when I
> middle click in its title bar [1]. But when I do on the 'title bar' of a
> GNOME application (e.g. Gedit) nothing happens. [2]
>

gtk3-nocsd?

gtk3-nocsd LD_PRELOADs a small library to disable the client
side decorations (CSD) of Gtk+ 3.

Since Gtk+ 3.10, its developers added a so-called header bar or custom
title bar. With this and the client-side decoration, the original title
bar and window border provided by the window manager are disabled by
Gtk+. This makes all Gtk+ 3 programs look like alike, but have different
handling from other windows on non-GNOME desktops. Even worse, this may
break some window manager or compositors.

Unfortunately, there is no reliable way of turning off CSDs in Gtk+
directly. This library makes this possible.