MainWindow Class

public class MainWindow : IWin32Window

Public Class MainWindow
	Implements IWin32Window

using System;
using Tekla.Structures.Dialog;
using Tekla.Structures.Model;

public partial class Form1 : FormBase
{
       // Handles the form load event.
       protected override void OnLoad(EventArgs e)
       {
           base.OnLoad(e);
           MainWindow.Frame.AddExternalWindow(this.Name, this.Handle);
       }

       // Handles the form closed event.
       protected override void OnClosed(EventArgs e)
       {
           MainWindow.Frame.RemoveExternalWindow(this.Name, this.Handle);
           base.OnClosed(e);
       }
}