Fix AtributeError when active_submenu is None.
Fix AtributeError when active_submenu is None.

release-engineering/kobo,pombredanne/https-git.fedorahosted.org-git-kobo,pombredanne/https-git.fedorahosted.org-git-kobo,release-engineering/kobo,pombredanne/https-git.fedorahosted.org-git-kobo,release-engineering/kobo,release-engineering/kobo,pombredanne/https-git.fedorahosted.org-git-kobo