Client-side decoration

[1] Sometimes client-side decoration is used to refer to the applications that don't have a traditional title bar.

However, this is a misuse of the phrase, as even applications that have a basic title bar can be client side decorated.

GTK was the first GUI toolkit on Linux that implemented client-side decoration using the GtkHeaderBar widget.

Universal Windows Platform applications can choose to draw their own title bars.

[6] Electron has the option to use a frame-less window (without toolbar, menu bar, tabs), however the application is responsible for drawing its own shadows.

Example of an application that uses Client-Side Decoration to draw its own window controls. (GtkHeaderBar widget on GNOME Files , 2014-01)
Deepin File Manager, a Qt-based application with client-side decoration.