picomiles on "_blank behavior"

Hi everyone here,

I am asking your help about an unespected behavior using target _blank.

Two sites hosted at the same provider, using buddypress and the same x2 theme, one a normal site, the other multisite.

In the normal site the links targeted using _blank, once clicked open new tabs, in the multisite the links open a new windows (or pop-ups).

Someone knows how to fix this strange behavior so that links using _blank target open new tabs and not new windows?

Here the normal site: http://pdtaranto.org
Here the multisite: http://ccnpatticentro.it

Thanks in advance

Nino