[development] Drag and Drop UI standards

[Andre Molnar]

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