Hi there
Note that clicking the popup itself will also close it.
Because of that, one might think of using an image to serve as the
"button". The problem here is that clicking an image on the popup
isn't sufficient to close it!
One possibility would be to create an image used as a
background image in a special style sheet .CSS file. I'm thinking
that because the image would be referenced that way, it may allow
working as you want. I'll have to test that later.
Just pondering out loud here... Rick