Add the possibility to generate the code in VB.NET instead of C#.
Put about 100 lines and set AutoSize to minimal width - you don't see all the lines as you cant scroll the message and what's moreover you can't even see the buttons (I used keyboard to move Inform...
Add the possibility to close automatically the box avec after a certain amount of time. A small counter will be added on the face of the default button.
Add a parameter to show or hide a checkbox "don't show this message again".
May I suggest the addition of a button to copy the contents of the message box to the clipboard? It is quite straightforward to implement and may be useful in various situations.
The label 'RightAligned' is truncated in the designer.