Do not override Treeview.enable_model_drag_xx for GTK4
In GTK 4 Gtk.TargetEntry is gone and replaced by Gdk.ContentFormats.
Although this makes the code work, there's still an issue in GtkTreeView that breaks DnD of tree view rows.
In GTK 4 Gtk.TargetEntry is gone and replaced by Gdk.ContentFormats.
Although this makes the code work, there's still an issue in GtkTreeView that breaks DnD of tree view rows.