I am using Gtkmm4, and lots of API has been removed. In Gtk3 one could use Gtk::Window::get_xid (inherited from Gdk::Window), but thats not possible anymore, because Gdk::Window has been renamed to Gdk::Surface, and Gtk::Window seems to not inherit from it anymore. But, one can always get the XId of a Gdk::Surface using GDK_SURFACE_XID(surface). How can i get the Gdk::Surface of a Gtk::Window, or alternatively, get the XId from a Gtk::Window directly ?
Note : i need only solutions using Gtkmm 4, not Gtkmm 3 !
The code that deals with the underlying surfaces got split off into a separate interface, Gtk::Native, which Gtk::Window then implements. Gtk::Native has a method get_surface() which should just work like Gtk::Window::get_window() did in GTK 3.