Insn't it wonderful when one reads the manual that answers appear?

On page 227 of the RibbonX book by Martin, Puls and Harding relating to dropdown controls that items in a dropdown element are only ever static and cannot be dynamic. That simple phrase culled from the page is the answer to my query above.

So the old adage still holds true: 'When all else fails: RTFM'

I'm now going to stand in the naughty corner as a penance!!