Description: $ImgTagFmt contains the attribute border that is not compatible with the XHTML-1.1 or -strict standards.
If we trust http://www.w3schools.com/css/css_border.asp the CSS property for border is known by NN4 and IE4, so support of older browsers should not be a problem.
I'd put a CSS definition into the template instead of the page header, because template designers might want to have the border black and white dished ;).
I changed $ImgTagFmt to be
$ImgTagFmt="<img src='\$LinkUrl' style='border:0px;' alt='\$LinkAlt' />";
so the border= attribute is replaced with a style= attribute. This gets images to XHTML-1.1 or -strict.
I could put the style into a stylesheet, but this could probably break a lot of existing skins, and there would have to be a class= attribute anyway. Skin designers who don't like the above can simply define their own $ImgTagFmt. :-)