Vernon,
Daniel answered your question on 27th May.
However there is a small problem. You might like to report it as a
bug.
a) The zoom you see in the box is that set in wysiwyg mode. It does
not refer to source mode.
b) The spinner works and changes the zoom level but the drop down box
does not work and is grayed out all the time.
c) Since the box is greyed out, once you change the zoom you have no
way of knowing it's value though it returns to 100% when you re-open
the file.
Not so bad after all.