AjaxControlToolkit.BlockingScripts missing in Ajax 3 ?

Question

Hi all

I have an old project that used an old Ajax control toolkit version

we need to upgrade the project to framework 3.5 and Ajax version 3

we have a class that used the old AjaxControlToolkit.BlockingScripts class, but this class is missing in the new ajax version

what can be the replacement for this class ?

thanks