This flickers while trying to drag the splitter out of bounds though. A Splitter::SetBounds(int min, int max) or something method might be nice, but I'm not sure how to go about this most efficiently.
I might be getting it completely wrong, since I'm still very inexperienced in UPP and GUI programming in general.
i am not familiar with splitter but i would go one of these ways:
first- the best, i guess - set the min size of the controls added to splitter, means overwrite the virtual Size GetMinSize() and calculate the 50% for the left and 30 (100-70) for the right control (or however they are placed)
second is to overwrite the Splitter class you would have to check in which function the resizing is done.