[Project_owners] Drag and drop to reorder a custom tree view

[David Murray]

Thanks a heap! I went poking through that and the Adblock Plus filters 
screen to see how they did it, then wrote a much simpler version for mine.

Neil wrote:
> David Murray wrote:
> 
>> I've got a one column custom tree view
> 
> You need to implement the drag and the drop separately.
> 
> For dragging you need to handle the ondraggesture event. Although you 
> can extract the mouse coordinates from the event to work out which cell 
> was dragged, the design of the tree means that the items you want to 
> drag are probably already selected.
> 
> For dropping simply implement the canDrop and drop methods of your tree 
> view; the tree body frame automatically passes you the correct row.
> 
> You can't avoid the ton of xpcom stuff needed to interact with the drag 
> service.
> 
> messengerdnd.js is an example of how to do dnd but note that the folder 
> pane uses RDF rather than a custom tree view so the call is slightly 
> different.