It could be the other dev has installed a Visual Studio extension that lets you do this.

>Hi all.
>
>This one is driving me crazy - it has tobe something in my local environment because another developer here does not encounter this problem.
>
>The project uses custom web.config transformations.
>
>I am modifying an existing MVC 3 application to run off of previously serialized data instead of hitting the database when in demo mode.
>
>Toward that end, I added a new config (web.demo.config) to web.base.config and added an attribute called IsDemo with a value of true.
>
>Now, when I debug in any other configuration (Test, for example), I can step through the code in the referenced assembly. I just cannot do so when debugging in demo Configuration.
>
>Another developer here has no probelm stepping through the code in the referenced assembly even when debugging in demo configuration.
>
>Any ideas what the problem could be?
>
>TIA