Remove unused code
This dates back to
Author: Cyrille Berger <cyb@lepi.org>
Date: Fri Oct 12 13:23:52 2007 +0000
detect if there is a visible widget, and if that's not the case, do not show the option dialog for png export, that makes it less cucumbersome to run kis_files_test svn path=/trunk/koffice/; revision=724499