disableContentMenu.js

if (window.Event)
    document.captureEvents(Event.MOUSEUP);

function nocontextmenu() {
    event.cancelBubble = true;
    event.returnValue = false;
    return false;
}

function norightclick(e) {
    if (window.Event) {
        if (e.which == 2 || e.which == 3)
            return false;
    } else if (event.button == 2 || event.button == 3) {
        event.cancelBubble = true;
        event.returnValue = false;
        return false;
    }
}
document.oncontextmenu = nocontextmenu;
document.onmousedown = norightclick;