here is a little more elaborate way of doing it. check that both the main prog and the message diagram looks a little different.
in this case the vi is dynamically called, but the front panel of the message has to be closed by itslef, unrelated to the main prog.
one advantage of this approach is that the main prog can continue all his tasks without waiting for the message to close. otherwise one would have to wait until finish of subvi, then close front panel, then continue rest of program (e.g. next loop iteration if the call was within a loop).
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... And here's where I keep assorted lengths of wire
s...