A zooming picture

Notice that there is a picture to the left. What we think will happen is that when you click on the picture, it will zoom bigger, and bigger, and bigger, covering over whatever may be in the way, like this text.

How it works

There are no global variables. After picture is defined, with an ID, you call zoominit, giving the desired small and large coordinates. This adds properties to the object, including dx & dy, integer increments for the 10 zoom steps.
Note the style for abszoom, it anchors the picture at the lower right corner of the window, and thus it zooms up and left. Simlarly, the comet is in the lower left. When they overlap, what comes last in the source is on top. Can probably vary this with the style z-index. I have now separated the zoom up and down into two functions, and on click, decide which one to call.
This is the bottom matter. It should be just under the original picture, and likewise liable to being covered up. (These buttons are no longer needed.)