Depends on D20337. Fixes T12167. Ref T13272. On this page ("Favorites > Edit Favorites > Personal", for example) the curtain actions aren't available on mobile.

Normally, curtains are built with Controller->newCurtainView(), which sets an ID on the action list, which populates the header button. This curtain is built directly because there's no Controller handy.

To fix the issue, just set an ID. This could probably be cleaner, but that's likely a much more involved change.

Edited my favorites, narrowed the window, saw an "Actions" button.