In this section:
Sometimes it is useful to invoke more than one call-back function at once. The "+" call-back function takes two subsequent call-back functions as arguments and calls each in turn. The return value from the "+" call-back function is the return from the second call. For an example of the use of the "+" and FILE_OPENR call-back functions see the description of %aw (Attach MDI Child Window) in Attach window. Note that the result of clearwin_string@('CALLBACK_REASON') reflects the original reason for the call-back and not "+".