GNOME Bugzilla – Bug 792476
Under Kwin on Wayland, titlebars are missing and instead appear on menus.
Last modified: 2018-01-18 18:02:23 UTC
When using KWin-Wayland, the titlebars on some GTK apps, tested with pavucontrol and midori, are missing. Instead, titlebars are shown on their right-click menus. GTK3 apps, tested with clamtk, show titlebars properly, as do Qt apps. Originally reported against KWin: https://bugs.kde.org/show_bug.cgi?id=388836
GTK+ 2.x does not have a Wayland backend: they are X11 applications. This looks like an issue in KWin's XWayland implementation, to be honest.
Nothing has changed in gtk2 with regards to window decorations in a long time.
Titlebars render correctly in kwin-x11.
looks like the kde side is not interested in pursuing this, seeing that the bug was closed as invalid.