First of all, thanks a lot to all the developers Nikolay, Lisheng ,James, Stefano , Pat and Gabriele for the great job done, I tried several application of this kind and this is the one which is very closer to my need - thanks. 

In re my question is more related to a fact that a portfolio doesn't have a default base currency so for instance if my base ccy is EUR and I buy a USD stock,  prices,gains,amount are shown in USD but actually summed up to the rest in EUR, is there a way to specify that an exchange must be applied?

I found a workaround on this calculating my self prices in the base currency but unfortunately I can't use any longer the "Refresh" feature because my price get overwritten.

Thanks for your job guys, I am really enthusiastic of this.

Alessandro