попробуй
<img id="imageInfoDialog" class="imgInfo" onmousedown="new function(e) { mouseDownInfoDialog(e || window.event,'aboutProgram'); };this.style.opacity=1;" onmouseup="this.style.opacity=0.8;" onmouseover="this.style.opacity=0.8;" onmouseout="this.style.opacity=0.5;" src="images/ico_info.png" alt="О программе" title="О программе" />