A bug_javascript technique to solve hot zone setting main entity through the Fromelement property of event object

When you click the "Set as primary entity" hyperlink, the original prompt box changes color and displays the contents: "has been set to merge primary entity."
Problem: When a hot zone box on the tip of the hyperlink under another hot zone B, click a hot zone prompt box hyperlink, will trigger B Hot Zone MouseOver event, causing a hot zone of the box will disappear.
This problem I have been puzzled for a long time can not find a solution, last week Zhou Jun prompted me to detect the source element of the event. I suddenly think of IE's event object has a property fromelement, tested it, sure enough, after clicking a hot zone hint box hyperlink, B Hot Zone mouseover event in the fromelement is null, so it's good to do, in the show hot zone of the prompt box function, Determines whether a fromelement is null, or return if null. To solve this problem, although this fromelement only exists in IE event.