Dragging items between collections always makes a copy

[tnajdek]

Behaviour should match the client, i.e. by default it's copy (showing plus icon), with a modifier key (cmd or shift depending on a platform) it's a move.

[tnajdek]

It seems react-dnd expects dropEffect (i.e. whether to show "plus" icon) to be configured upfront, i.e. it cannot be easily changed while item is being dragged. Alternatively, if not defined, the default behaviour is that if "alt" is pressed, it's "copy", otherwise it's "move". It doesn't seem to allow overriding that default behaviour, which is oppositie of what we want and also uses wrong modifier key, without replacing the entire "backend".

I suspect we will need to either fork react-dnd or roll out our own drag-n-drop solution. Let's park this for now.

[tnajdek]

https://forums.zotero.org/discussion/86588/moving-items-between-subcollections

[tnajdek]

Moving should also be possible via "Add to collection" dialog to ensure feature parity on touch and for keyboard-only users.

[tnajdek]

https://forums.zotero.org/discussion/comment/406503

[tnajdek]

https://forums.zotero.org/discussion/69575/how-to-move-entries-from-one-collection-to-another