Yep, when I said plugins I meant either editor tools, or runtime plugins that also contain custom editor features.
I have one work in progress plugin for realtime plotting of property values during PIE. One possible use for this was to limit properties displayed in a dropdown list to only those marked with a custom ‘Volatile’ metatag, so that the dropdown wasn’t flooded with all sorts of properties that it didn’t make any sense to plot over time. That way users could add this tag to properties in blueprints that they wanted to be available for plotting.
At one point I was working on a project where I created a custom blueprint type (I mean deriving from UBlueprint) which had it’s own editor, incorporating a custom node graph alongside the regular blueprint tab. I wanted a way to allow the user to control which of their blueprint variables got exposed for use in my custom graph, which then resulted in some special binding information for only those properties being added to the generated class. I hijacked the ‘Expose on Spawn’ meta, but obviously that’s far from ideal.
Far from common use cases, granted, but I’ve no doubt I’ll eventually have more, and I’d have thought it would be fairly straightforward to implement. The addition of an editable array of metatag key-value pairs after the ‘Defined Property Flags’ section would be enough. I could look at a PR for that when I find some time, if it’s something you’d consider.
Of course a more structured interface would be nice, like you say some automated generation of details panel rows, but that would require some kind of meta-meta-data defining known meta tags and what form they take, which would be a much bigger task and is perhaps getting a bit too crazy.