[Wine] Where wine writes?

[etwineb]

I'd like to know where wine writes.
I am not speaking about applications wine executes, they can obviously write everywhere the user privileges allows (via z:/), but of wine itself.

I saw that even using WINEPREFIX wine writes in ~/.local, sometime it leaves .desktop files around.

Why is that? When wine writes exactly?
Can I force wine keeping everything it needs in its WINEPREFIX folder?

(reason: I made few packages of windows applications, they should work most possibly as linux native ones)

thanks, a RTM answer is fine if you point me in the right direction.