i really liked the "immediate mode" GUI model but unfortunately the current state of the best one, Gio, is pretty poor in the widget department, and best practices for ensuring minimal wait to do the painting is far from settled, i had lots of fun with that stuff, built a couple of extra wingdings for it when i was working on it (a scrollbar, for one) and was in the process of building a searchable log viewer tool but we didn't get the bugs ironed out before we ran out of runway

my colleague was very ambitious but wasted so much of his time in stupid things, by the last 1/4 of the process i was basically left to clean up his mess and of course you know how much longer it takes to fix stuff than build it