>>You've done well, I think
>>
>>Your original question : Is it possible without having a separate project for this class?
>
>Well, nothing is simple in the .NET world :(
>
>When I try to debug the page where I added this custom class I'm now getting
>
>Error 124 Assembly 'AjaxControlToolkit, Version=3.0.20229.20843, Culture=neutral, PublicKeyToken=28f01b0e84b6d53e' uses 'System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' which has a higher version than referenced assembly 'System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'
>
>Which is a bit strange why does it say about AJAX instead of my new control?

Maybe it uses ajax controls

And yes, nothing is simple. It's a hughe learning curve ...