Component Properties question

An old juce expert told me that he vaguely remembered that I could
use Component properties to save off the current state of components
(e.g. which tab is currently active) when a user closes the app, so it
can have the same appearance when it next opens.

I don’t see anything that would save component properties to registries
or file automatically. Was there something like this before, or was this
just wishful thinking?

If there’s nothing like that now, what would be the easiest way to gather
up the current state information and save it for the next run?

No, that’s not what component properties are for, but it is what the PropertiesFile class is for…