User-16411453 posted
You can try using <div> or panels, and zindex them in the proper sequence. Make 2 panels and give them the same coordinates, but the 2nd one has a higher z-index value. The use png images with transparency to overlay the div below.
Or load the image as a background image, and create your control so it overlapps the background image, but is on the primary layer.
You calculate the distance by getting the current x of the right anchor - current left of the left anchor using javascript or jquery.
I don't see this as being a server control question, but more of a css or html question in general.