Window icon is not shown in gnome shell dash under wayland

[rastersoft <raster rastersoft com>]

Hello:

I created several applications that make use of Gtk.window, and set a 
window icon. But recently I discovered that, under wayland, the icon is 
not shown in the dash, but under X it is shown fine. It fails both in 
python3 and Vala applications.
In both cases I used Glade to generate the window, and set the icon name 
there.
What can I do to have again the right icon in the dash?

Thanks