if (document.all) {
}
else if (document.getElementById) { 
    document.captureEvents(Event.MOUSEDOWN)
}
else if (document.layers) {
    document.captureEvents(Event.MOUSEDOWN)
}

document.onmousedown = mousedown_handler

function mousedown_handler(mouse_event) {

    // This is the message that will appear
    var no_right_click = "Sorry, right-clicking is not allowed!"
    
    if (document.all) {

        //Probably Internet Explorer 4 and later
        if (event.button == 2 || event.button == 3) {
            alert(no_right_click)
            return false
        }
    }
    else if (document.getElementById) { 

        // Probably Netscape 6 and later
        if (mouse_event.which == 3) {
            alert(no_right_click)
            return false
        }
    }
    else if (document.layers) {

        // Probably Netscape 4
        if (mouse_event.which == 3) {
            alert(no_right_click)
            return false
        }
    }
}