timer1.Enabled = false;
this.Close();

public class clsGlobal

public sealed class clsGlobal 

public static frmMDIMain g_objfrmMDIMain;
//this is to declare a global static reference to our MDI parent so that the same 
//instance is referred across all child with no extra line of code

using System.Windows.Forms;

[STAThread]
static void Main() 
{
	Application.Run(new Form1());
}
// because we cannot have two Main function.We are invoking everything from clsMain

mnuWindowCascade and text &Cascade
mnuWindowTileVertical and text Tile&Vertical
mnuWindowTileHorizontal and text Tile&Horizontal

private static frmSChild m_SChildform;
public static frmSChild GetChildInstance()
{
	if (m_SChildform ==null) //if not created yet, Create an instance
		m_SChildform = new frmSChild();
	return m_SChildform;  //just created or created earlier.Return it
}

//This is to make sure that when we Click on a 'New Single' menu on Parent form twice 
//it should not open two instance of the same child form

frmSChild objfrmSChild = frmSChild.GetChildInstance();
objfrmSChild.MdiParent = this;
objfrmSChild.Show();
objfrmSChild.BringToFront();

frmMChild objfrmMChild = new frmMChild();
objfrmMChild.MdiParent = this;
objfrmMChild.Show();

try
{
	if(this.ActiveMdiChild.Name =="frmMChild")
	{
		frmMChild objfrmMChild = (frmMChild)this.ActiveMdiChild;
		objfrmMChild.Close();
	}
	else
	{
		frmSChild objfrmSChild = (frmSChild)this.ActiveMdiChild;
		objfrmSChild.Close();
	}

}
catch
{
}

Application.Exit();	

this.LayoutMdi(MdiLayout.Cascade);

this.LayoutMdi(MdiLayout.TileVertical);

this.LayoutMdi(MdiLayout.TileHorizontal);

frmAbout objfrmAbout = new frmAbout();
objfrmAbout.ShowDialog();