When would I need scroll locking
On the web, when you create an overlay/modal/dialog you usually begin by using the CSS:
position: absolute;
top: 0;
left: 0;
right: 0;
bottom: 0;
This is great, you can give this new <div>
a transparent background and it's children a solid background and then you have a modal. It is at this point that you realise the page you…