Created attachment 154820 [details] GTK+ 3 example program to reproduce the bug. Under kwin wayland, GTK+ 3 applications are unable to become clipboard owner via gtk_clipboard_set_with_owner() or provide data via callback. STEPS TO REPRODUCE Compile the attached cot.c file, instructions for compilations are at the beginning of the file. Run "./cot" and then press the button on the main window. The application will try to become clipboard owner and provide a small string of text. But when you paste text in other windows, nothing is pasted, no clibpoard callbacks are called in cot.c. See also this Remmina bug: https://gitlab.com/Remmina/Remmina/-/issues/2737 The example program shows that text is pasted with no problems under KDE+Xorg, GnomeShell+Wayland, GnomeShell+Xorg. But under KDE+Wayland text is not pasted to the destination application window. OBSERVED RESULT Nothing is pasted when the users try to paste. Callbacks of gtk_clipboard_set_with_owner() are not called. EXPECTED RESULT Application should become clipboard owner and provide clipboard content when the user pastes to another window. SOFTWARE/OS VERSIONS Linux/KDE Plasma: KUbuntu 22.10 + backports PPA to have latest plasma (5.26.4)
"UTF8_STRING" is not a valid mimetype. I can see kwin copy that, but no client will think it has readable clipboard contents. If I change your example to "text/plain" or "text/plain;charset=utf-8" it works as expected. The way mimetype's name themselves is a bit random. We do have a translation of text mime names for x11 applications in kwin, as well as some translations inside the Qt wayland backend to make apps use the right standard. Presumably mutter has a translation layer for wayland apps too, which helps hide this? But ultimately this is still a client bug and should be fixed at the root. Can you confirm that this resolves the real problem in Remina?
FYI: if you open krunner (alt+space) and type "kwin" you can get a kwin debug console. There is a tab called "Clipboard in there" which can view contents.
Thank you, changing UTF8_STRING to text/plain;charset=utf-8 worked. You saved me ! ;) But I need to do more regression testing to ensure text/plain;charset=utf8 works also on older (max 4-6 years) Xorg. If it does not work, the application (Remmina) should expose two different formats to the clipboard, I think.