I'm using dotNet V1.1, C# .

I create a class library as follows:

using System;
using System.Web.UI.WebControls;
using System.Windows.Forms;

namespace ClassLibrary1
{
    public class Class1
    {
        public Class1()
        {
        }

        public static void SetVar(ref System.Web.UI.WebControls.TextBox reportVar)
        {
        }

        public static void SetVar(ref System.Windows.Forms.TextBox reportVar)
        {
        }
    }
}

I have created this library so that it can be used by both Windows Forms and
Web applications - see the overloaded forms of the SetVar() method. This
class library compiles successfully.

I then create a Windows Forms application with a reference to this class
library. The relevant snippets are below:

using ClassLibrary1;
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;

namespace WindowsApplication1
{
    public class Form1 : System.Windows.Forms.Form
    {
        private System.Windows.Forms.Button goButton;
        private System.Windows.Forms.TextBox textBox1;

// Usual VS-inserted stuff goes here, and my own method to respond
// to clicking on a button is shown below.

        private void goButton_Click(object sender, System.EventArgs e)
        {
            Class1.SetVar(ref textBox1);
        }
    }
}

So, my application is a Windows application making use of my class.

When I compile this, I get the following error.

error CS0012: The type 'System.Web.UI.WebControls.TextBox' is defined in an
assembly that is not referenced. You must add a reference to assembly
'System.Web'.

Why is this happening? Surely my application should only need to reference
the assemblies that provide the classes that it actually makes use of? I'm
pretty sure that with C/C++ I wouldn't have had to link against a static
library that I wasn't using, even if another library that I was using had a
function that used a type from the unlinked library. I can't find anything in
the C# specification that explains this behaviour.

More importantly, how do I fix this so that my Windows Forms application
does not have to reference System.Web?