private void button2_Click(object sender, EventArgs e)
 {
     SomeOtherClassDoingStuff.DoSomethingByCallbackInterface(this);
 }
        private void button1_Click(object sender, EventArgs e)
        {
            var x = SomeOtherClassDoingStuff.DoSomethingThatReturns();

            HandleSomeReturnValue(x);
        }