GtkWindow::set_destroy_with_parent

Sets whether or not the window should be destroyed with its transient parent. If destroy is true, the window will be destroyed when its transient parent is destroyed. If destroy is false the window will still exist after its transient parent is destroyed.

This method is most commonly used for dialog windows and sub-windows of an application. If destroy is true, the window will be closed when the user (or application) closes the main window.