You know, it never occurred to me to do that with actors. I've always used VI server properties. That lets me preconfigure the panel before the user sees it.
I checked with a few internal resources on this.
On a desktop, there is no issue with using the VI Properties dialog to set an actor core to show its front panel when called.
Things get more complicated on RT. It appears, on our more recent cRIO targets with embedded UIs, or when debugging is enabled, that you can use both the SubVI Node Setup right-click option and VI Properties to configure a VI to show its front panel when called, at least in a trivial case. We have had issues in the past with doing this, so I would tread lightly, but it seems to work as of LabVIEW 2015, on our newer controllers.
We'll look into this some more, and possibly revise our guidance.
