Hi Barbara and welcome to our community
Are you possibly confusing a Highlight Box with a Click Box?
A Highlight Box really should never be transparent. Its
purpose is to highlight or call attention to an area on the screen.
A Click Box is used in the same way a button is. It provides a way
to allow your user to click to interact with your movie. Buttons
and Click Boxes look a bit different.
You might want to insert an image of a screen on a slide.
Then insert Click Boxes that are invisible and link to slides that
perhaps provide explanations of the area that was clicked. This is
just one way you might use a click box.
On the other hand, a button is just that. A visible
indication that something will happen when your user clicks it.
Perhaps Larry or another person here can better explain
things if I managed to munge it and muddy the waters.
Cheers... Rick