Question

I have an interesting problem..
I have a Form that launches another Form (2) through a Button. Before Form2 Closes, it sometimes fires an Event which Invalidates Form 1 and forces Form 1 to refresh it’s data. The problem I have is After Form 2 fires the event, Form 1 seems to get it and handles it, and refreshes it’s data and Only then Form 2 Closes. I want Form 2 to Fire the event and Close, BEFORE Form1’s event handler catches and processes the event.
I have a feeling it is related to BackgroundWorker (sort of like SwingUtilities.InvokeLater in Java) .. but I am not that experienced with it ..

public class Frm1{

void LaunchForm2(){
   Frm2 form2 = new Frm2();
   form2.dataChanged += new DataChangeListener(myListener);
   form2.showDialog();
}
private void myListener(){
  //get my data again
}

}

public class Frm2{

 private void Close(){
    if(myDataHasChanged){
      if(dataChanged != null) { 
        dataChanged(); 
      }
      this.Close();
    }
 }
}

Answer 1

You can raise the event after calling Close – calling Form.Close will not exit the method that called it.

EDIT: Try using BeginInvoke to wait for the next message loop before handling the event, like this:

form2.dataChanged += delegate { BeginInvoke(new DataChangeListener(myListener)); };

2^nd EDIT: To give Form1 a chance to repaint, call BeginInvoke twice to wait two message loops before updating (One to close Form2, and a second to repaint Form1), like this:

form2.dataChanged += delegate(parameters) { 
    BeginInvoke(new Action(delegate { 
        BeginInvoke(new DataChangeListener(myListener), parameters);
    }));
    //Or,
    BeginInvoke(new Func<Delegate, object[], IAsyncResult>(BeginInvoke),
                new object[] { parameters }
    );
};