docs for windows, framebuffer

[Havoc Pennington <hp redhat com>]

Hi,

Could the respective developers put a couple paragraphs of helpful
information in:
  docs/reference/gtk/windows.sgml
  docs/reference/gtk/framebuffer.sgml
  
This could perhaps be copied from docs we currently have in text
files. I want to get rid of all the text files so we get all the docs
into the manual and discoverable on the web site.

Havoc