Had to add Reference to System.Web

I'm using the Runtime version 4.0.30319 of the Aspose.PDF dll.

Whenever I create a Aspose.Pdf.Facades.PdfFileEditor object, I get a compiler error in my project:

The type 'System.Web.HttpResponse' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Web, Version=4.0.0.0, v

Why would this be? When I add the System.Web assembly to my project the error goes away. Is this class doing something that has the web as a dependency?

To make sure there was no other error with my solution/project I created a complete different solution and created this object and got the same result.

Thanks,

Sean