New SubPanel Implementation: Use Terminals

[JackDunaway]

SubPanels are the life of the party for scalable HMI projects. I use SubPanels inside of SubPanels inside of SubPanels. Currently, when you drop a SubPanel, all you get on the BD is an invoke node:

If you delete that one invoke node, you have no indication on the BD whatsoever that the SubPanel still exists! If you have hidden that SubPanel and have no references to it on the BD, it's a nightmare trying to re-show it through the VI server (especially if it's nested, or in a Tab Container). Further, there is no method that allows you to query the SubPanel what VI is currently inserted into it.

Here's a suggestion for updating the implementation. The "datatype" of the SubPanel is a VI reference, so you can directly write to it or read from it without an Invoke Node. This also allows the parent to query what VI is currently inserted. The "Insert VI" and "Remove VI" Invoke Nodes could go away (wire null ref for "Remove).