function ffContextMenu(e) { if(document.getElementById) { if(e.target.tagName=="IMG") { return false; } } }
function nsRightClick(e) { if(document.layers) { if(e.which==2||e.which==3) { return false; } } }
if (document.all) {
 document.oncontextmenu = function(){ if (event.srcElement.tagName=="IMG") return false; }
} else if (document.getElementById) {
 document.oncontextmenu =  ffContextMenu;
} else if (document.layers) { 
 document.captureEvents(Event.MOUSEDOWN);
 document.onmousedown = nsRightClick;
}