Sounds interesting and useful
I've created many menus in the past , and all I have to say is , in order to get it bug-free , you'll have to spend a lot of 'boring' time on it. Maby this tool will provide a better solution.

Btw , if you havent tought of that , you could implement Snap for panels and buttons (to place new panels near old ones , or buttons for example.) and also Snap to the grid lines...It'll make aligning easyer.