Online Visual Designer v1.0 won't load - Javascript error

I keep getting a Javascript error with online visual designer…

I’m running Windows Vista / IE 8 and in compatability or non compatability mode I get the same error…

Line: 25358 Character: 4 Code: 0 Error Message: Object doesn't support this property or method URL:
I have debug bar installed which has given me these error details.

All i see is a blank page

Existing version of online editor is not compatible with IE8
You need to use IE9 or any other modern browser.

( the code produced by designer will work in old versions of IE, but designer itself requires a modern browser )