I have never, for the life of me, found a quicker way to go from zero to GUI than Tcl/Tk. Even VB requires a lot of rat wrestling to set up a UI. Some people think that's how it should be done, but compared to just telling the machine what you want and letting it take care of layout, to me it's still cumbersome. Plus, Tk has had hierarchical, relative positioning and sizing, no need for doing layout in terms of absolute pixels or "dialog units", from the jump.
Also Tk is in every language, as it's dumb easy to duct tape it into C. TkInter, Perl-Tk... I'm pretty sure if some Forth user created a Tk UI for PForth/GForth, it would be almost as easy as in TCL, but with the syntax reversed. That's it, you would find 'pack' in the end of a sentence full of words.
I have never, for the life of me, found a quicker way to go from zero to GUI than Tcl/Tk. Even VB requires a lot of rat wrestling to set up a UI. Some people think that's how it should be done, but compared to just telling the machine what you want and letting it take care of layout, to me it's still cumbersome. Plus, Tk has had hierarchical, relative positioning and sizing, no need for doing layout in terms of absolute pixels or "dialog units", from the jump.