System.Windows.Forms 1.0.5000.0 2.0.0.0 System.Enum This enumeration is used by the class. Specifies constants defining the default button on a . Field System.Windows.Forms.MessageBoxDefaultButton The first button on the message box is the default button. 1.0.5000.0 2.0.0.0 Field System.Windows.Forms.MessageBoxDefaultButton The second button on the message box is the default button. 1.0.5000.0 2.0.0.0 Field System.Windows.Forms.MessageBoxDefaultButton The third button on the message box is the default button. 1.0.5000.0 2.0.0.0