"It's up to the user to decide; that's all." No your saying the themer should decide, by adding a list of widgets that work.

read the thread: http://www.lsdev.org/e107_plugins/forum/forum_viewtopic.php?985.0
get THC4k's OTS3 prop: http://www.ls-themes.org/index.php?cat=article&show=ots3
see if his implementation works.