I feel the doc at IFMsgBox which states:
would be much clearer if it were worded something like:Known limitation: If the MsgBox contains only an OK button, the return value will indicate that the OK button was pressed if the MsgBox times out while its own thread is interrupted by another.
Known limitation: If the MsgBox contains only an OK button, and it's thread is interrupted, and it times out during the interrupt, upon resumption of the thread the return value will indicate that the OK button was pressed.