Live selection dialogs

Calling AfterTransformation on selection dialog items everytime when OnChange is called = live selection dialog

What would be the result? Something like what RuleSet is doing on a standard screen? I.e. recalculating some values live? What are the use cases?

Yes, recalculating some values live - between bound items. Example from real life - sugar beet factories have different date of campaign start. When I choose proper factory, I need recalculate date of campaign start. I do it by AfterTransformation but user see wrong date on OK click.