cssStrangeness

Funny Image Click 2

If I define:
a.imageHoverButton:active {
background-color: #f00;
}
then define an image inside a link using that style:
<A class="imageHoverButton" HREF=""><img src="blah.gif" border=0></A>
then in IE and Opera it works as expected. The BG goes red when clicking on the image or the square area surrounding the image. But, in Firefox it only changes the BG color if I click on the whitespace around the image. Clicking on the image itself won't change the BG color.