According to helpfile, timeout parameter in MessageForm is set in milliseconds:

I specify one with a timeout of 5000 milliseconds, and F5
Let's wait, and wait, and wait ... and click after more than 1 minute.

It runs as expected when set to 5: is timeout in seconds or milliseconds?

Apparently in seconds...the underlying code uses milliseconds.  I will look at the docs and make sure they are correct and verify what you are saying is accurate, but if it is working this way, it has not changed in years.  So I would just move forward and if I learn something different I will let you know.

Nothing has changed in years

http://forum.strataframe.net/Topic4847-10-1.aspx?Highlight=timeout

LOL...clearly that never made it on the list   We will update the docs for the 1.6.6 build.