MessageDialog
Description:
public MessageDialog (string primary_text, string secondary_text, Icon image_icon, ButtonsType buttons = CLOSE)
  
  Constructs a new Granite.MessageDialog. See Granite.Dialog for more details.
Parameters:
| primary_text | 
           the title of the dialog  | 
      
| secondary_text | 
           the body of the dialog  | 
      
| image_icon | 
           the GLib.Icon that is displayed on the left side of the dialog  | 
      
| buttons | 
           the Gtk.ButtonsType value that decides what buttons to use, defaults to Gtk.ButtonsType.CLOSE, see Granite.MessageDialog.buttons on details and what values are accepted  |