C#

namespace Win
{
	public class Form1 : System.Windows.Forms.Form
	{
		private System.Windows.Forms.Button button1  = new Button();
		private System.Windows.Forms.Button button2  = new Button();
		public System.Windows.Forms.Panel panel1;

		public Form1()
		{
			InitializeComponent();
		}

		static void Main() 
		{
			Application.Run(new Form1());
		}

		private void button1_Click(object sender, System.EventArgs e)
		{
			this.Close();
		}

		private void button2_Click(object sender, System.EventArgs e)
		{
			Form2 f2 = new Form2();
			f2.Show();
		}
	}// Form1

	public class Form2 : System.Windows.Forms.Form
	{
		private System.Windows.Forms.Button button1 = new Button() ;

		public Form2()
		{
			InitializeComponent();
		}

		private void button1_Click(object sender, System.EventArgs e)
		{
			// at a specified condition :

			Button b = new Button();
			b.Text = "Hello" ;
			Form1 f1 = new Form1();
			f1.panel1.Controls.Add(b);
		}

	}// Form2
}// namespace Win