I’m wondering if I should try the RichText box’s change event, or its lost-focus event, or provide a click-to-preview button (last resort because it’s another component to manage). I haven’t yet tried the change event anywhere, so I don’t know if it fires just for an initial character input of a RichText box, or for every character as they type (which would be cool, but could be a performance drag; or maybe not). The latter (fires for each character change) makes more sense.
I was supposed to be working on Data Bindings and Form attribute capturing (i.e. subject of this question) when I ran into not having a Markdown TextArea component available. I’ll get back to that after solving this Markdown preview situation.
EDIT: I’ll just use a separate card component for this markdown composing need with a TextArea, RichText and Button (to click to update the preview). Then I’ll just hide / unhide the entire card. That’s easier.