Thanks, i'll work on those issues. I know why ESC doesnt work, thats easy to fix.
Otherwise, looks useful? Im more than happy to hear feedback on other issues, like overlay colors. The red seemed to be the most visible. I cant do anything that would add pixels, like borders or whatever.
How it works is, i use the config file to find UI elements on the page, then create divs the exact same size as those UI elements. I give those divs a bg color, and an opacity so you can see the original element. Finally I overlay a div over the whole screen with a click handler so you cant click on any elements.