I'm reminded of an old project called Entity that sadly disappeared (I may have an old snapshot from before their site went down somewhere), where someone had built a GUI designer where you linked GUI events to code live. One of the supported languages was C, in which case on change the code was passed to GCC and compiled into an .so and swapped into the process the same way as here (it also supported Perl and JS, I think; it was an odd beast... And you could edit the code of the GUI designer from within the GUI designer itself)