What GUI toolkit to use for an embedded system?

Does anyone here have any suggestions for a good GUI toolkit (such as GTK, 
Qt, etc) suitable for an embedded system?


Small size is obviously of interest, but the intended target is a 
prototype and we should have a fair bit of headroom.

I've been thinking about using Python for the GUI bit at least for now, in 
order to get something up and running quickly, but that could be 
negotiable.


Already settled on py-qt, but it turned out not to work on my desktop 
machine due to a missing dependency.  That, in turn, has another 
dependency - which won't compile.  That made me think that perhaps this is 
the place for something smaller and simpler with fewer moving parts.


[ I'm sure that GTK is worth the trouble for desktop apps, but perhaps not 
if all you need are buttons for a user to push and some general status 
indicators.  (Time and temperature readouts, and that sort of thing.) ]


MAgnus