window.open to center of screen

Question

I am using window.open to open a popup window like so:

Answer 1

Edit

This is a bad answer. a much better answer can be found here: window.open() on a multi-monitor/dual-monitor system - where does window pop up?

But in the meantime while i decide when i want to update this answer, this fiddle accounts for dual monitor setups: http://jsfiddle.net/w665x/138/

Original Answer

This might work for you. Not confident in it being entirely cross-browser, but close;

blah

Fiddle!