Multiple Instances

First, well done on build 622! I do have one question though:

Why can't I have multiple instances of Idea open at the same time? Previous releases have allowed me to do this without any problems.

I'm currently working on two projects, one in development and one undergoing testing and bug fixes. It's been really handy to have two Ideas open at the same time and being able to quickly switch between the two. My machine is powerful enough to handle multiple versions, so can I have this option back please?