C#

using System.Diagnostics;

//get info on current proc
Process proc = Process.GetCurrentProcess(); 
//get array of process w/ same name
Process[] procs = Process.GetProcessesByName(proc.ProcessName);            
//if there is more than one
if (procs.Length > 1)
    Application.Exit(); //exit
else
    Application.Run(new Form1()); //else run the app

f.propName = my vlaue;<br />
f.show();

public class MyClass
{
  public static event EventHandler Created;
  public MyClass()
  {
    // Initialize.
    // Fire static event.
    if (Created != null) Created(this, EventArgs.Empty);
  }
}

public class MyClass
{
  public MyClass()
  {
  }
  public event EventHandler MyEvent;
  protected virtual void OnMyEvent(EventArgs e)
  {
    if (MyEvent != null) MyEvent(this, e);
  }
}
public class MyClass2 : MyClass
{
  public MyClass2()
  {
  }
  protected override void OnMyEvent(EventArgs e)
  {
    // The EventArgs (or derived class) is passed so
    // that derived classes can check specific states.
    if (e != null) DoSomething();
    // Call the base class so that listeners can handle the event.
    base.OnMyEvent(e);
  }
}

 private int x,y;<br />
 bool click=false;<br />
 bool first=false;<br />
 private void Form1_MouseMove(object sender,System.Windows.Forms.MouseEventArgs e)<br />
 {<br />
   if(e.Button==MouseButtons.Left)<br />
   {<br />
	if(click&&first)<br />
           this.Location=new Point(this.Location.X+e.X-    x,this.Location.Y+e.Y-y);<br />
	x=e.X;<br />
	y=e.Y;<br />
	click=true;<br />
	first=!first;<br />
	}<br />
	else<br />
  	click=false;<br />
<br />
	}<br />
<br />
	private void Form1_Load(object sender,   System.EventArgs e)<br />
	{<br />
	x=this.Location.X;<br />
	y=this.Location.Y;<br />
	}

protected override void WndProc(ref Message m)
{
	if (m.Msg == 0x0084)
		m.Result = (IntPtr)2;
	base.WndProc(ref m);
}