.NET (Core and Framework)

        protected override void WndProc( ref Message m  )
{// Message Values found in WinUser.h
    if( m.Msg == 0x0114  // WM_HSCROLL
        ||  m.Msg == 0x0115 )    // WM_VSCROLL
    {
                  // ...do something..
    }
    base.WndProc( ref m );
}

public void InitMyForm()
{
   // Adds a label to the form.
   Label label1 = new Label();
   label1.Location = new System.Drawing.Point(54, 128);
   label1.Name = "label1";
   label1.Size = new System.Drawing.Size(220, 80);
   label1.Text = "Start position information";
   this.Controls.Add(label1);

   // Changes the window state to Maximized.
   WindowState = FormWindowState.Maximized;
   // Displays the state information.
   label1.Text = "The form window is " + WindowState;   
}