not sure if I get you right... Tk::EntrySet is a composite designed to enter multiple values/selections where the underlying -entryclass allows for a single value/selection only. Just make a selection (or enter a value) in the last (empty) entry, and a new field will appear. Delete contents of an entry, hit return and the entry will disappear.
So instead of having one widget with multiple selection capability, you get a dynamically growing/shrinking set of single selection widgets. Your program will not talk to the entries but to the wrapping Tk::EntrySet instance which provides a simple API for a multiple value widget. You can always access the list of selected values with $entry_set->valuelist.

Can you point us to an example of a widget matching your requirements (Possibly one that is implemented in another UIFramework)?

I appreciate your taking the time. I learned something new with this approach and put the code in my snippets. But this widget will be used in a form and growing set of widgets will mess the whole form up. I need something more like a an browseentry box with drop down listbox functionality that acts as a drop down menu ). I use a button with a listbox in a toplevel which I pop under on demand for a different form widget and think I might impliment something like that for this but use a entry widget of some sort. thanks