C#

this.Closing += new System.ComponentModel.CancelEventHandler(Form_Closing);

private void Form_Closing(object sender, System.ComponentModel.CancelEventArgs e)
{
   e.Cancel = true;
}

private void Form_OnClosing(object sender, System.ComponentModel.CancelEventArgs e)
{
    e.Cancel = true; //prevents the form from closing
}

α.γεεκ

Fortune passes everywhere.
Duke Leto Atreides

Process.Start(@"c:\Program Files\Microsoft Visual Studio .NET 2003\Common7\Tools\vsvars32.bat", 
@"regasm.exe /unregister [path to your file] /silent");

class T{delegate void D();static void Main(){D d = new D(Main);d();}}

class T{delegate void D();static void Main(){new D(Main)();}}

class Example {
	delegate void StatusOutput(string text);

	static void Main() {
		DoSomeWork(new StatusOutput(System.Console.WriteLine));
		DoSomeWork(new StatusOutput(Alert));
	}

	static void Alert(string text) {
		System.Windows.Forms.MessageBox.Show(text, "Status Update");
	}

	static void DoSomeWork(StatusOutput output) {
		output("Working...");
		System.Threading.Thread.Sleep(2000);
		output("Done");
	}
}

void Test()
{
  string str="UnModified";
  RefTest(ref str);
  //str now == "Modified!"
}

void RefTest(ref string s)
{
   s="Modified!";
}