I've looked somewhat at both, and my impression is that Gtk+ tried to do a similar thing as the Xt Intrinsics, but didn't do it in a really better way. The pro

I've looked somewhat at both, and my impression is that Gtk+ tried to do a similar thing as the Xt Intrinsics, but didn't do it in a really better way. The problem with both is that you still have to write a lot of boilerplate by hand. Of the Xt Intrinsics I know that the things you could do with it were pretty advanced for their time, just too much annoying work. What the Gtk+ people should have done is design some nice notation for objects and generate the Xt Intrinsics object boilerplate from that. Or in fact that should have been done soon after creating Xt.