void gtk_window_set_transient_for ( GtkWindow* window, GtkWindow* parent )
Dialog windows should be set transient for the main application
window they were spawned from. This allows
[window managers][gtk-X11-arch] to e.g. keep the
dialog on top of the main window, or center the dialog over the
gtk_dialog_new_with_buttons() and other convenience
functions in GTK+ will sometimes call
gtk_window_set_transient_for() on your behalf.
parent unsets the current transient window.
On Wayland, this function can also be used to attach a new
GTK_WINDOW_POPUP to a #GTK_WINDOW_TOPLEVEL parent already mapped
on screen so that the #GTK_WINDOW_POPUP will be created as a subsurface-based window #GDK_WINDOW_SUBSURFACE which can be positioned at will relatively to the #GTK_WINDOW_TOPLEVEL surface.
On Windows, this function puts the child window on top of the parent, much as the window manager would have done on X.
Parent window, or
The argument can be
The data is owned by the caller of the method.