those can be on the stack?

I really don't like the double map.
each map is a tree and this is slow to append.
can we use a enum instead of a name for the map, thus moving from map to vector?

everytime you call .keys() you generate a new list appending things in a temporary. if the keys never change we should store this value somewhere.

const

why explicit when it has no parameters?

QByteArray on the hash if used without UTF8 strings

This widget is created with no keys. We do not know how many clients will add.

I can not answer that since i didn't write this . It doesn't like when i give it a parent so it remains unchanged.

QString is for label names as well as the key.

dude, move this back to the initializer list, and pass 'this' there. :)