Currently, links included in forum posts that are supposed to open in a new window use the attribute target=_new.

This will not open the link in a new and unnamed window. It will open the link in a window named "_new". While the first click on a link in a forum post will most likely open a new window, subsequent clicks on such links will reuse that named window.

The proper way to always open a link in a new and unnamed window is target=_blank.