I try to print the expression tree in this Code completion and STM32 peripheral registers (http://forums.next.codeblocks.org/index.php/topic,21823.msg148463.html#msg148463), and I found the wxtreelayout class(only exists in wx 2.x, but removed for wx 3.x) is quit interesting.
It is not finished, but I can show a screen shot, still not finished yet. :)