Do "in browser" not working?

[Simon Smith]

I've been trying to execute some basic JavaScript tests in the IDE on OSX.

*on* mouseUp
>    *do* "result = urlParams" in browser
>    *-- put "12131232" into myScore
> *   *-- do "alert ('"  & myScore & "');" in browser
> **end* mouseUp

However although the script compiles, the debugger complains and I can;t
get anything to work. There is no mention in the help either - has this
feature been dropped somewhere along the road?