The Structured Keywords Panel can be invoked in 2 ways. The first is global, from the Image menu bar (or ctrl-shift-k). The second is for a single image, from the drop down arrow next to keywords in the Metadata (IPTC) Panel.
In the former case, there is the option to append or replace new keywords added, via a tick box. The collection can be cleared and replaced, but its content can still be appended without affecting other keywords (if append is selected via the tick box).
In the latter case, invoking the Structured Keywords Panel includes all existing keywords in the collection in the single image concerned, but whatever ends up in the collection replaces the entire keywords of the image. Therefore, you cannot clear the collection to add a just a new selection of keywords, without overwriting the existing keywords.
My request is that the two Structured Keywords Panels should act in the same way. That is, the version accessed from the Metadata (IPTC) Panel should also have an "append" tick box, so that you can clear the collection but still append the keywords you select, without overwriting the existing keywords.
There is a discussion of the issue at: http://forums.camerabits.com/index.php?topic=13755.0
Thank you for considering.
Has anyone else run into this as a problem? If so, please upvote the suggestion. Thanks!
An alternative to an append tick box might be to have the option (accessed by the modifier key) for the Clear button to cut the current collection to the clipboard, instead of simply deleting the contents of the collection. This would leave the collection empty and uncluttered while a new collection is created. The previous collection could then be pasted back in, either to the collection or in the Metadata (IPTC) Panel, once new keywords have been added and dealt with in the now empty collection.