Update issue #136 and #63 : Make sure modeless dialogs have correct parent window
Filters dialog still seems to have null parent window for some reason.
If parent window is NULL it will get set to App::GetMainWnd() which may be the wrong document window.

git-svn-id: http://graph-studio-next.googlecode.com/svn/trunk@235 c2f33eb2-41b2-391d-4cb4-d9d0608729ba