OK, This is crazy. I'm using 8.2:
I created a sub-VI that is essentially a dialog box. it is a string display with OK and CANCEL buttons beneath it.
There is a string control that is used to feed the string indicator from a calling VI. After one of the dialog buttons is pressed, I feed an empty string to a property node of the string indicator before closing the sub-vi.
I am using it in a VI that feeds a string constant into this dialog VI.
While testing it I found that after the dialog closes, my string constant, that was feeding it, goes blank.... bearing in mind that the string constant is not even in the dialog sub-vi, but in the calling VI.
However, if I replace the property node with a local variable, it works fine.
???
Chuck