I think we have five of these editors now: Herald, Bulk Edit, Owners Package Paths, Custom Policy, and now Trigger Rule. Depending on how you want to count, the action stack on comment forms is also a similar editor.

I think they share a mostly-reasonable amount of code already. All but the action stack use "MultirowManager", which is super ancient but not too terrible. The newer ones (bulk edit, comment forms, trigger rules, maybe owners?) share PHUIX controls for rendering the actual dropdowns and text inputs and stuff, although the older ones (herald/policy?) could be updated. They do all have some amount of unique behavior. For example, Herald has two sections for conditions/actions, and conditions has three columns for [ field ] [ operation ][ value ]. Owners has an AJAX validation callback and an associated UI. So they're never going to share all of the same code, and the pieces that need to be specialized vary from instance to instance.

I think this stuff probably could be cleaned up a bit and more code could be shared, but it doesn't feel too bad to me right now.