Reduce drag-and-drop jank on dashboards
- Currently, you can drag panels underneath the invisible "there are no items in this column" div and the "Create Panel / Add Existing Panel" buttons. This is silly; stop it.
- Currently, when viewing a tab panel on a dashboard, you can drag the panels inside it. This is extremely silly. Make "movable" off by default and pass it through the async flow only when we actually need it.
- Make the whole "Add Tab..." virtual tab clickable to open the dropdown. This removes the rare exception/todo combo I added earlier. F
- Add or remove some icons or something.
Test Plan: Moved panels around on dashboards. Tried to drag panels inside tab panels. Added tab. Things were less obviously broken.
Reviewed By: amckinley
Maniphest Tasks: T13272
Differential Revision: https://secure.phabricator.com/D20415