gtk-window-titlebar (window)

window -- a gtk-window widget
widget -- a gtk-widget object to use as titlebar

Accessor of the custom titlebar widget of the window.

The gtk-window-titlebar function returns the custom titlebar for the window. The (setf gtk-window-titlebar) function sets a custom titlebar.

If you set a custom titlebar, GTK will do its best to convince the window manager not to put its own titlebar on the window. Depending on the system, this function may not work for a window that is already visible, so you set the titlebar before calling the gtk-widget-show function.