[Boa Constr] ogl support

[Mathew Y. <my...@jp...>]

Hi
I want to make it possible to add a ogl.ShapeCanvas from the palette. 
Has anyone already done this? I reading the documentation on "Extending 
Boa" and looked at the code for ScrolledWindow. It looks like a big job 
so hopefully someones already  done it.

Mathew