The current OpenGL button are hard to see on a grey backdrop and hi-res display. I suggest giving us the ability to change the text size (as well as the button size) and also pick colours we like, rather than just use red and green (neither of which works that well on a mid-grey canvas).
Also, when you click the '2D' OGL button it disappears, rather than change colour and remains as a toggle switch. If you hit it by mistake you have to go to the options panel and set the height value to get the object back as '3D'.
I would also like the ability to interactively scale shingles/roof tiles. Not everyone works to real world scales (also, I thought you could scale them in LW CAD on LightWave anyway...)
Oh, and more presets would be nice :-)