Editing a viewed set drops the first character

[Cisien]

When editing a set not in the "your sets" list, the first character is dropped and the editor loses focus.

This is due to how a set gets "promoted" to being a "Your set" instead of being ad-hoc (downloaded just to view).
The specific mechanism is that this promotion happens when the set gets marked "dirty" by typing in the editor. This happens before the content is persisted from the model, so when it's moved from the adhoc set to the uploads list, the data gets lost and the editor's model is re-generated.

Possible Fixes:

• Grab the model contents and set that before promoting the bundle, and then re-focus the editor after the promotion is done
• Make the editor read-only on viewed files, with a UI element for editing it. Clicking the UI element would promote the set similar to how clicking the "new" button works.
• ???