Taxonomy filter exposed to user that dynamically only includes terms attached to currently published content Background:
a) Taxonomy: I have built as site that allows users to tag content of a particular content type with tags.  The system started with a pre-existing taxonomy before any content was added, but has grown organically as users add content and terms of their own.  What this means, of course, is that at any time, some of the terms in the taxonomy, may not be attached to any currently published content.

b) View with Exposed Tag Filter:  As a means to allow users to find material of interest, I have exposed the Tag Field as a filter for a tabular view of the content.  The Filter is a drop down list.  When a user selects a tag from the list, the view is appropriately filtered to the matching items.

Problem:
As the taxonomy has grown, a good proportion are not, at any time, attached to any content.  Thus, it is frustrating for the user to filter the table with a tag list that includes these terms, as they yield 0 results.

Requested Help:
Therefore, I am looking for a way, that the terms shown in the tag filter are dynamically limited to only those that are attached to currently published content.  It is not clear to me how to do it.  I would greatly appreciate any advice on how this may be accomplished.
You should have a look at Views Selective Exposed Filters, part of the Views Hacks module. It will limit the taxonomy terms to those in your view's result set.