Existing functionality in Zotero Standalone allows an item to be dragged to a tag to add it. I find this somewhat counter-intuitive and naturally want to drag the tag to the item instead. Is it possible to add this functionality?

This would get confusing, though, if multiple items were selected in the middle pane.

Similarly, it would be great if I could add related items by dragging them into the related items page. For example, I like to add the chapters of a book as related items to the entry for the book itself.

This wouldn't work, if you think about it. Selecting an item in the middle pane changes what's in the right pane, so there'd be no way to select other items to drag. We could support it for multi-window dragging, but that would only be possible in Firefox, since Standalone doesn't allow multiple windows.

I could maybe see being able to drag (or right-click-drag) items onto other items and have that display a context menu with some options, including one for relating them. That's a little awkward, but it's what Windows does with right-click file dragging (with options to "Copy Here", "Move Here", "Create Shortcut Here").

As to your first point, how is it more confusing than the current functionality where multiple selected items all get dragged to the tag?

Because the current way there are multiple objects dragging to a single target, which is a standard UI convention. It's not confusing at all. Your way, you would be dragging a single object to multiple targets, which is not a standard convention, and it's totally unclear what should happen—i.e., whether the tag should apply to just the item you're dragging over or to all of the selected items (or whether the drag should just be disallowed). In a filesystem, you can't select multiple folders and then drag a file to all of them.

I agree very much on the second point, making the Related tab a drop target for items.

Currently it is not possible to drag items to the related page, the only way is to do press the Add button and select the relevant items.
The problem with this is that the view of this list is different from the one of the main panel.
Let's say I do a fulltext search, and would like to relate all of the results to one of the items found. I click on the item, related, add.
Now I have a differently ordered list of all items in the library and have to search again.
Dragging items to the Related tab is very natural from a UI standpoint.

Thanks, Gracile, for mentioning Zutilo. I hope the 'relate selected items' will be integrated into zotero, this would be an extremely useful addition.

@Dan: I see your point, but maybe we can come up with another solution to make the process easier.
Setting items as related takes too many steps at the moment.

Some ideas:

1: Have an icon on the Related tab that reads 'Drag over item to add' (similar to how tags work)

2: Have a modifier that allows selecting items in the middle pane without bringing up the right pane.

3: Have a button on the Related tab that freezes the currently selected item so that one can then drag onto the related pane.

4: A list of recently selected items, you could drag to that list

5: Right drag, like you mentioned.

6: Select all items, right click and relate. This is n:n instead of n:1 like the other methods, both have advantages and disadvantages.

7: Initialize the Add related pop up dialog with the same view the middle pane has.

Only reason for integrating Zutilo's relate is that currently few people use related because it is too cumbersome to use and probably don't know about Zutilio (I didn't), and that it might break in the future if Zotero gets updated.
Otherwise Zutilo works very well.

Two Cents.

Make it so that any title in the center panel will relate to any other item at the title level when dragged on top of it. Create a similar note-level-to-note-level function, as neither of these actions currently performs a function.

You would have to invoke some key+drag to associate notes with titles, of course. That would be handy, too.

But I will take a look at this Zutilo thingy.

m