Comment 36 for bug 597825

(In reply to comment #17)
Links from comment 17 were no longer valid, but I did find this explanation for managing state of accelerators:
http://blogs.msdn.com/oldnewthing/archive/2005/05/03/414317.aspx

This meshes with comment 11, that the message does get passed up to the top window.

Off to look for where these messages would even go...