actually Norman was talking about filters not legends. I tested that with different compinations and also faced the same issue every time. So maybe xml file should be edited somehow because dropdown filters have certain point for screen size when they work normally and after that point they will be just like in Norman's picture.
Ville, you are correct. (My bad.) If someone creates an Idea for fixing this (or at least getting control over it) I'll vote for it.
thanks for your replies.
A bit unfortunate that such a "basic" feature is not available in Tableau.