Unhappy to search a solution like others users and read some pretentious people who define themself as advanced user or experts and who NEVER answer the question and provide a solution.
I'm unhappy also to see that, like me, many users don't understand the doc from QT and then, can not use this doc for learn or use the QT tools.

Also, i can see that: ONLY novice has been able to answer this question by an exemple (a little bit heavy and lake of information in the code... but better than "advanced auto proclamed" users has been able to product for help).

I think for all this prouve from 2010 to now (2015 the next month, QT/Digia can consider that his doc lake of clarity and can not be usuable by someone don't make the QT code. So that in fact, this doc is a datasheet, and not really a doc.
That's why, QT/Digia could think about this could be better for users/ futurs clients to have a real clear doc (construct by some workers who can clearly write a doc accessible by ALL) inline and take care about some of this kind of self defined "experts/advanced users" who never prouve this kind of to big pretentions and by this way, desserve the image of DIgia.

So... for this MODEL proxy and setup implementations way of coding, particulary, the doc serve nothing more than make confused more the users (except this kind of auto proclamed experts... who serve nothing more than make you loose your time).
Lake of informations / documentation on this difficult part of QT greatfull tool.

why 5 years without have somethinbg more serious about that ? i don't know... Maybe Digia not understand he has to win more to be clear/more accessible for everybody and not only for auto-proclamed experts/advanced users...

hope this can be understand, it is easy to understand to.