Positioning not working in fixed size window

```
SimpleModal 1.4.2 jQuery 1.8.0 IE8

I cannot get my modal to correctly auto-position when the window it is in has a 
fixed size, i.e. it is opened using 
`window.open(...,width=800,height=600,resizable=0,status=0,toolbar=0)`.

Otherwise excellent library.
```

Original issue reported on code.google.com by `CaswellP...@gmail.com` on 4 Sep 2012 at 9:13
