Messagebox counting down - possible?

hi,
can you tell me if it is possible to make messagebox, that appears only for defined seconds i.e 5 seconds, and if user doesn't take any action(change default button) the messagebox will disappear.
example:
If the user does not press no button in 5 seconds NO is assumed.

  MessageBox MB_DEFBUTTON2|MB_YESNO|MB_ICONQUESTION "Skip licence?" IDYES Skip 

hmm, maybe that's possible with some api-calls through the system.dll plugin.
i'll see what i can do.

for references about api-calls, look here:
Microsoft Development Network (MSDN)

it is somehow certainly possible, only i don't know how. I have seen this thing in program demos, informing user that they are using demo version, and giving two opportunities, whether to run demo, or to register program.

Probably it can be possible using an external silent program executed before MessageBox sending a message to the installer through SendMessage to close this message box.

I didn't test to send the message ${WM_CLOSE}, but as the description shows, it tries to close the program passing through program's code to do it (so not everytime it can close the program).