What exactly do you mean by an "instance" of Zotero? Two separate Standalone processes running separate profiles? That certainly won't work, since dragging transfers only ids, not data, and I don't really have any interest in implementing that given existing Import from Clipboard functionality.
Dragging between two Firefox windows using the same data directory used to work (and the same would probably apply to Standalone), but I think that's broken and has been disabled for a while.
Dan, yes, I did mean "Two separate Standalone processes running separate profiles." I won't try to detail why it would have been useful, but such functionality makes sense to me according to the ways in which I use Zotero. Anyhow, thanks much for your work on those many other excellent features that you have implemented! Mark
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Dragging between two Firefox windows using the same data directory used to work (and the same would probably apply to Standalone), but I think that's broken and has been disabled for a while.