Why use a owner window in MessageBox.Show?

Question

MessageBox.Show has forms like MessageBox.Show( ownerWindow, .... ).

What do I gain by assigning a owner window?

Answer 1

Calling MessageBox.Show(frmMain,"a message","a title") adds the form TextDialog to the application's Application.OpenForms() forms collection, along-side the frmMain Main form itself. It remains after you close the Messagebox.

I just discovered 14 of these when I called btnOK_Click() and set a breakpoint.

When I called frmMain.Close() to close the main form, nothing happened. frmMain will not close until all 14 of the Application.OpenForms are closed as well or else you must call Application.Exit().