Ken Rickard wrote:
1) Do we have any best-practice guidelines on using drag-and-drop?
2) Specifically, if the action requires saving the state change, should that save be automatic (on-drop) or user initiated (extra button or link on-click)?
Well when developing the UI for WebFM (which has a drag and drop as well as right-click context menus triggering event) we asked ourselves (and the toronto drupal user's group) about when certain actions *should* be triggered. In the case of WebFM - when attaching a file to an existing node via a right click operation - we *could* have very easily attached the file (and updated the node) as soon as the action was taken (and in fact this was our first instinct). But the consensus was that users expected that the attach (or even an attachment re-order) operation should only happen when the node was saved by the user clicking on submit. The use case: User goes to edit a node User starts attaching new files (or re-arranging existing attached files) with the tool. User then decides - they don't actually want to change the node after all. User clicks away. User later discovers that even though they didn't click 'submit' - changes had been saved. Certainly an unexpected result. So I think any setting that *could* be changed via drag and drop should only be changed with an explicit 'submit'. andre