Hm. I've just found that ```ChangeWidget(..., :Value)``` is not type safe. When ```:Items``` consists of ```list<symbol, string>``` it accepts string. I thought that ```:Items``` are indexed by the symbol in this case (they are). However when I use value out of ```:Items``` the ```ChangeWidget``` uses it as current value (but do not store it into ```:Items```)

So, I'll add some more refactoring / fixes.