Does System.Windows.Forms.Form work in Fiddler script?

[Ed]

I know it uses Jscript.NET but is there some special context it runs within (and is documented somewhere) that would prevent me from instantiating a Form to input a string, select from a radio button group, etc? Or is a different file supposed to be edited?

When I try to add the following to CustomRules.js in the ScriptEditor, it says "ERROR LINE --> MyForm myform = new MyForm() - The list of attributes does not apply to the current context" when I save the script.

 

Here is the Form class I am trying to use to make a dialog:

import System.Windows.Forms;
import System.ComponentModel;
import System.Drawing;

class MyForm extends System.Windows.Forms.Form {
    // declare variables
    private var label1: Label;
    private var textBox1: TextBox;
    private var button1: Button;
    private var panel1: Panel;

    // constructor
    function MyForm() {
        //SuspendLayout(); // suspend layout events
        // label, size, and center form
        Text= "Resize Me!";
        ClientSize= new System.Drawing.Size(300,300);
        StartPosition= System.Windows.Forms.FormStartPosition.CenterScreen;

        // create a label
        label1= new Label;
        label1.Location= new Point(10,10);
        label1.Size= new System.Drawing.Size(80,20);
        label1.Name= "label1";
        label1.Text= "Label";
        label1.Anchor= AnchorStyles.Left;

        // create a TextBox
        textBox1 = new TextBox;
        textBox1.Location= new Point(10,30);
        textBox1.Size = new System.Drawing.Size(80,20);
        textBox1.Name= "textBox1";
        textBox1.Text = "Hello World";
        textBox1.Anchor= AnchorStyles.Left;

        // create a Button
        button1= new Button;
        button1.Location= new Point(200,240);
        button1.Size= new System.Drawing.Size(80,20);
        button1.Name= "button1";
        button1.Text= "Button";
        button1.Anchor= AnchorStyles.Right | AnchorStyles.Bottom;

        // create a Panel
        panel1= new Panel;
        panel1.Location= new Point(0,0);
        panel1.Size= new System.Drawing.Size(300,300);
        panel1.Name= "panel1";
        // resize panel on resize form
        panel1.Anchor= AnchorStyles.Top | AnchorStyles.Left | AnchorStyles.Right;

        // add controls to the panel
        panel1.Controls.Add(label1);
        panel1.Controls.Add(textBox1);
        panel1.Controls.Add(button1);

        // add panel to form
        this.Controls.Add(panel1);

        //ResumeLayout(); // resume layout events
    } // end_constructor
} // end_class



class Handlers {

    ...

    static function BeforeTestList(arrSess: Session[]): boolean
    {
        MyForm myform = new MyForm();
        myform.ShowDialog();

        return true; // Test should proceed; return false to cancel
    }
}