$ snap run jdim
Sat Dec 25 09:15:59 2021 (ER 0) : SmcOpenConnection failed.

(jdim:3904): Gtk-WARNING **: 09:16:01.382: Allocating size to gtkmm__GtkWindow 0x55e8c7ee62a0 without calling gtk_widget_get_preferred_width/height(). How does the code know the size to allocate?

となります