Question about MessageBox with Component Interface

If think-time message boxes like below are not executed by CIs, what would be the &return value?  Would it be NULL?  In that case, would the "Else" be executed below?

&return = MessageBox(36, "", 10000, 92, "Do you want to update item catalogs with your category changes?");

If &return = 6 Then

....do something

Else

... do something else

End-If;

I'm using a delivered component.  I prefer not to modify the delivered PeopleCode.  We want the "Else" portion of the above "If" statement to be executed by the CI.  If that's happening, then we won't have to do additional coding.

Thank you.