Minor simplifications to layoutView

Changing `_buildRegions` like this seems more consistent with the rest of the lib IMO
Well not that this is a good argument but I have never seen `Boolean` used like this. (I am sure i can find examples on github) 

But the verbose version of this method is at least a bit more transparent. This is not a big issue tho, just something to talk about, since we have been trying to keep the code base __very__ readable