GTK+ 3 applications such as nautilus, evince, gthumb, midori, etc. do not have title bar displayed in KDE Plasma. According to GitHub project gtk3-nocsd, this is caused by the header bar and client-side decoration introduced by GTK+ 3.10 and further versions.

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 alike. Even worse, this may break some window manager or compositors.

Unfortunately, the Gtk+ developers decided to be against the existing standards and provide “no option” to turn it off.

It is cumbersome to add a customized window rule for each GTK+ 3 application. The definitive solution is to install the Debian package gtk3-nocsd.

img

img