I just noticed your framerate in the screenshots. Either you are on a terrible machine, or that will need some optimizing.
Well both. I have a compaq wndows xp 2002. And 3 days ago I figured out how to use hint brushes.
At first making maps around 5000 brushes gtk radiant would crash while compiling, at-least 2 or 3 times.
After adding hint brushes that problem went away. Now I'm working with 5700 brushes and now it crashes only once.
But I'm still having trouble with hint brushes.