Allow me to re-open this issue, as I have discovered a couple of issues
that I think ought to be addressed before this can be considered completed.

To start with the high-order bit: I think in its current form (even
after addressing the immediate issues) this harness isn't quite ready to
be part of Roundup's core. It is too much tied to tracker-specific
aspects, such as a 'keyword' entity in the schema, or a particular HTML
layout.

I thus suggest this code to be moved into tracker-specific extensions.
(This won't affect the functionality at all, just the code layout.)

Now some specific problems:

1) After (re-)discovering what was already reported in msg4204 (the
disappearance of the "(edit)" link once the keyword value was set), I
attempted to validate the generated HTML, and noticed that it was
invalid. This may be the cause for the reported behavior.

2) The KeywordEditor module attempts to inject HTML by means of the
"innerHTML" DOM attribute. However, that only works with HTML 4, but not
XHTML. Since otherwise Roundup isn't tied to HTML 4 (in fact, it has a
config value to set whether XHTML should be generated), I think this
needs to be fixed, too.