gtk_decoration_layout
Description:
Determines which buttons should be put in the titlebar of client-side decorated windows, and whether they should be placed on the left or right.
The format of the string is button names, separated by commas. A colon separates the buttons that should appear on the left from those on the right. Recognized button names are minimize, maximize, close, icon (the window icon) and menu (a menu button for the fallback app menu).
For example, "menu:minimize,maximize,close" specifies a menu on the left, and minimize, maximize and close buttons on the right.
Note that buttons will only be shown when they are meaningful. E.g. a menu button only appears when the desktop shell does not show the app menu, and a close button only appears on a window that can be closed.
Also note that the setting can be overridden with the [property@Gtk.HeaderBar:decoration-layout] property.