You can create a sub-vi that is closed until called. Under "Window Appearance" in the "VI properties" there is even a selection called Dialog. You have the sub-vi open when called (and close when released) have a loop that waits for the user to make a selection (and possibly hit enter or whatever to signal that the selection process is complete). You can have a text indicator that is passed values from the calling VI to allow passing messages, etc. If you use an enumerated type for the selections, its value may then be passed back to the calling routine. To see how NI originally did dialogs, open up their "Three Button Dialog" as one example. A dialog box need not be as complex as the "Three Button Core", it was made to be flexible.
Good luck and have fun.
Putnam Monroe
PutnamCertified LabVIEW Developer
Senior Test Engineer North Shore Technology, Inc.
Currently using LV 2012-LabVIEW 2018, RT8.5

LabVIEW Champion