He removed the [mouseOver-styled] cover image (for 'button 1') that I had on the popup layer 'btn1'. Note that as you traverse down the popup menu, the 'button 1' image reverts to the mouseOff state (blue, not orange). While that doesn't solve my problem (I want/need the popup layer to indicate button 1 is currently active), it does explain the behavior reference in my initial post.

Given that explanation, I'll work toward a satisfactory solution (given the framework of my personal requirements). If/when I come up with an alternative, I'll post it. Certainly, if anyone else beats me to it ... I'm always happy to learn. Mercí.