Why is rtcMsgBox calling my Visual Basic procedures?

Normally, any Windows messages that a Visual Basic native-code program receives are processed by a top-level message pump in the program. If the program receives a Windows message that triggers a Visual Basic subroutine or procedure, the top-level message pump calls the routine.

One exception, however, is if your program displays a MsgBox. In this case, the program calls the internal function rtcMsgBox (in Msvbvm50.dll or Msvbvm60.dll), which contains a separate message pump to process the Windows messages until the MsgBox is dismissed.

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