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 to e.g.
keep the dialog on top of the main window, or center the dialog
over the main window.
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 Windows, this function puts the child window on top of the parent, much as the window manager would have done on X.
The argument can be
The data is owned by the caller of the function.