It is true that sometimes "Undo" would be very useful. In my case, it happens I accidentally delete title when editing it, or when copying a title to a wrong field (for instance, when creating a new item and copying title name from the source, I accidentally click on a different item, and overwrite its title). I know it is my own fault, but... Errare humanum est...
JR

I'm new to Zotero and have just deleted a note from a reference because I wasn't aware that the icon I was clicking on was a delete icon (I thought it closed an expanded item). Having read another discussion thread I see that an undo feature is difficult to add. What about a message saying 'Are you sure you want to delete this?' then? I know it would slow things down a bit, but it does add an extra check that might save users from that sinking feeling as they delete something that they may find difficult to recreate.

Just a thought...

k_chandler: 1) There's already a confirmation dialog for deletes. 2) Deleted notes go into the trash. 3) I don't know what you clicked, but there's no delete icon in Zotero. The only way to delete an item is via the keyboard or context menu.