Disabling middle click pasting doesn't work only in Chromium...; Works in KDE

[sinni800]

Hey, so this is an interesting observation I made when trying to get rid of middle click pasting:

In firefox, we know it's a separate setting (groan, but okay). But in Chromium, for example, I find that disabling it in the KDE settings app disables it in Chromium, so they listen to the DE's settings in some way!

Though, when I turn it off in hyprland, it stays completely enabled in Chromium.

Due to the issue behaving in this way, I think there may be something that Hyprland can do (I'm not sure what though) to disable it in chromium as well.

Reading Hyprland source, the setting only really sets so the "primary clipboard setting" action is ignored (from quick-eyeing the code). But looking at KDE source code, I found that it just sets a setting for kwin, which, on launch (and probably during runtime somehow), either creates a "PrimarySelectionDeviceManagerV1Interface" or doesn't.

Going to Chromium, they have two implementations for the "primary selection device", one being "zwp_..." and one being "gtk_...", here.

Now I have no idea what this means (having not dabbled in Wayland primary selection clipboard stuff at all past the cursorly exploration I did just now), and maybe someone else has a better insight into it, but there has to be a cut somewhere on why KDE manages to disable the Chromium middle click paste with its main option, and Hyprland doesn't.

I know there are similar discussions, but not specifically on this variant of the issue. It otherwise works, just not on Chromium.

Also as a funny aside, in another Electron instance here, it doesn't work on either KDE or hyprland, so that's that...

[Gliczy]

Hi, it seems like Chromium is finally getting an "official" way to disable middle click pasting: https://issues.chromium.org/issues/399412221. It looks like most of the necessary changes are merged already, with only one missing.
So, this should no longer be an issue in the near future.

Unrelated to your issue, but you mention that only Chromium misbehave, what about programs using Qt?
In my case, both Chromium and Qt based applications are still allowing middle click pasting.

[sinni800]

Ah, very cool. So it's really because Chromium implements it custom (which gets down to Electron) and that the deactivation is buggy when you activate Autoscroll?

Qt programs work perfectly fine, by the way. I also went into Gsettings and set it there for Gnome programs.

In the case of Qt programs, I think using KDE's system settings and disabling it there did something...

[Gliczy]

I'm not sure how Chromium handle the primary clipboard under the hood. The changes linked in the Chromium issue (which are now all merged!) will make it so Chromium read and follow the GTK preference for middle click pasting.

The first version with these changes should be Chromium 144, which should release in January 2026.

As for Qt, I have tried in KDE settings and it does work for KDE Plasma itself, but Hyprland will still paste on middle click for Qt windows. Maybe I should open a separate discussion for this. There is already a discussion for this #10713.