... the zcite tags content is inaccessible unless you deactivate the tag. I don't want to change that, and don't know how... When the cursor is to the left of the tag, and I press the right-arrow, the cursor jumps to the right end of the tag, and then the tag is highlighted with the light-blue box. So far so good, because now I can use Backspace to deactivate it, or Tab to call the editCitation function...
The problem is that when I push Ctrl-PageDown or use the toolbar icon to call traverse-next, TeXmacs bombs with an invalid cursor error. It's also broken whenever there are zcite tags in the document even when trying to traverse between other kinds of tags. In a document with nothing in it but a number of \strong{strong content} tags in it, I can traverse-next and traverse-previous with no problem. But when I insert any zcite tags between those, I can not traverse-next, but I can traverse-previous. I noticed that with the \strong{} tags, it leaves the cursor at the start of the tag's content when I traverse-next, and at the end of the content when I traverse-previous.
So for the zcite, where the content is inaccessible, the traverse-previous, which leaves the cursor in a valid location, works fine, but the traverse-next is broken, because it produces an invalid cursor location.