child window (used to implement e.g. #GtkEntry)
foreign window (see gdk_window_foreign_new())
offscreen window (see [Offscreen Windows][OFFSCREEN-WINDOWS]). Since 2.18
root window; this window has no parent, covers the entire screen, and is created by the window system
subsurface-based window; This window is visually tied to a toplevel, and is moved/stacked with it. Currently this window type is only implemented in Wayland. Since 3.14
override redirect temporary window (used to implement #GtkMenu)
toplevel window (used to implement #GtkWindow)
Describes the kind of window.