The arcpy help can be found here.
So the messagebox can be defined as such:
MessageBox(message, title, {mb_type})
To use you just pass in a message and title as text. The mb_type is the type of messagebox type value. It supports the following types:
mb_type | value |
---|---|
0
|
OK Only
|
1
|
OK/Cancel
|
2
|
Abort/Retry/Cancel
|
3
|
Yes/No/Cancel
|
4
|
Yes/No
|
5
|
Retry/Cancel
|
6
|
Cancel/Try Again/Continue
|
Complete Example:
>>> import pythonaddins
>>> result = pythonaddins.MessageBox("Press Cancel", "TITLE", 1)
>>> print result
Cancel
Simple Right!