Here an event handler in a link changes an image outside the link. Each image has a unique name so it can be addressed separately. The two images are GIF's of the same size. The "off image" is invisible because it is a rectangle of the color defined as transparent.

(Code adapted from Clarence Eldefors' Arrow onMouseover at JavaScriptKit )

<SCRIPT LANGUAGE="JavaScript">
<!--

var imgon = "graphics/on.gif"
var imgoff = "graphics/off.gif"

function imgover(imgname){
     imgname.src = imgon ;
}

function imgout(imgname){
     imgname.src = imgoff ;
}
//-->
</SCRIPT>

<img name="Arrow02" SRC="graphics/off.gif" width=20 height=10 border=0> 
<a href="http://www.janusmuseum.org/panabasis/main.htm" target=blank
onMouseOver="imgover(Arrow02)" onMouseOut="imgout(Arrow02)">Panabasis</a><br>