No that is not my point. The OpenGL bindings are mature as far as I know. The point is that binding Gtk is much less effort than reimplementing a GUI toolkit in Julia. By the way: Gtk.jl state is ok. Its just that it could be even better.
For me these are still orthogonal things. You can of course also manipulate visuals with Gtk/Cairo. Just have a look at applications like Inkscape where this is intensively done. Or in my application shown in the screenshot above you can click into the image an the 4D image is appropriately sliced.
What you can’t do is putting widgets into the graphic context, that is true. This is something which is usually done when developing games or other highly specialized software.
But I actually don’t want to say anything bad about any effort to implement a widget library in Julia. Just go for it, if it matures I would be very happy to test it. The only point I wanted to make is that Gtk+Julia already are a nice thing for implementing small user interfaces for interacting with scientific data and its not so bad relying on a toolkit that most Linux users are using anyway on their desktop.