The ‘holy grail’ of UI toolkits for interpreted/JIT compiled languages is a solution that works without further compilation/linking activities and without major installations. Something like this is available with toolkits/libraries that have simple+clear C-APIs (see ccall). With this background i’d rather call Gtk.jl a powerful GUI solution that works on ‘the’ three major platforms (minus rendering problems with Fonts or HiDPI).
I’d not assume that everyone can simply install a VC++ redistributable in her/his Windows setup, even if she/he wants to.
Don’t get me wrong, i’d like to see QML or similar Qt based UI succeeding, but we’re importing too many dependencies with the current approach.