In theory you can send the images over as X backing stores and do just that. But I'm not sure it was implemented that way. I remember GTK 1 was well optimized

In theory you can send the images over as X backing stores and do just that. But I'm not sure it was implemented that way. I remember GTK 1 was well optimized for X and you could run GTK applications over slow modem lines quite comfortably. GTK 2 went a different direction entirely and became almost unusable over the Internet. I doubt GTK 3 or 4 are any better now that they're designed for compositors.