var clickmessage="Copying of images on this site is strictly prohibited."

function disableclick(e) {
    if (document.all) {
        if (event.button==2||event.button==3) {
            if (event.srcElement.tagName=="IMG"){
                alert(clickmessage);
                return false;
            }
        }
    }
    else if (document.layers) {
        if (e.which == 2||e.which == 3) {
            alert(clickmessage);
            return false;
        }
    }
    else if (document.getElementById) {
        if (e.which==2||e.which==3) {
            if (e.target.tagName == "IMG") {
                document.oncontextmenu = new Function("alert(clickmessage);return false");
                return false;
            }
            else {
                document.oncontextmenu = new Function("return true");
            }
        }
    }
}

function associateimages() {
    for(i=0;i<document.images.length;i++)
        document.images[i].onmousedown=disableclick;
}

if (document.all)
    document.onmousedown=disableclick
else if (document.getElementById)
    document.onmouseup=disableclick
else if (document.layers)
    associateimages()