Moving messages between threads

[edemaine]

Problems split and join. We need a UI for moving one thread inside another, and for splitting a message off into its own thread. Continuation of #13. [Tomohiro]

• [x] Allow dragging messages between windows (currently causes an exception)
• [x] Action/Reparent as summarized below

[edemaine]

Natural interface:

• [x] New Action button "Reparent" causes a modal dialog
  • Actually the same as messageParentConfirm but no longer called "confirm".
  • Starts with a blank preview in top right
• [x] Top right has a new typeahead box that lets you type:
  • [x] Message ID (as I currently do when reparenting)
  • [x] coauthor:id
  • [x] https://coauthor.../group/m/id URLs (from copy/paste)
  • [x] Partial title of thread
  • [x] Partial title of group name (but perhaps only the same group is possible by anyone but superuser of this group)
  • [x] Placeholder text could say "Message title / message ID / group name"
  • Note: this is a more discoverable way to reparent within the same thread too! Could mention in hover that this is doable via drag/drop interface too.
  • Note: this works on mobile, unlike drag/drop.
  • Note: autocomplete maybe restricted to loaded messages = root messages and messages within this thread? Unsure; alternatively, could have an "all message titles" subscription... In any case, could enter message ID of any message, including those not loaded.
• [x] Should not list the message itself as a possible parent
• [x] Should not list descendants of the message as possible parents
• [x] As you select choices in typeahead, you get preview in top right corner.
• [ ] Perhaps also as you type?
• [x] Allow raw message IDs that don't match
  • [ ] Ideally fetch messages via roundtrip to server
• [x] Button to Move and another button to make the message its own root.
  • Then get a confirmation dialog showing the move, as in current dragging interface.
• [x] In particular, propose to forbid moving message from group A to group B (because it changes access control) unless you are superuser of group A.
• [ ] Moving from one thread to another can still change access control, for partial members. Ideally should warn about any users who have access in thread A but not thread B (and vice versa?) so that the user can make an informed choice.
• [ ] When making a message into its own root (starting new thread), default behavior should probably be to inherit all partial members from the source thread. Deviation from this requires admin access to change ACL.

[edemaine]

I've implemented most of this, including Action/Reparent and the typeahead box. Can type in the group name to move message to root. Testing would be appreciated.