<div style="background-color: red; width:100px; height:100px; position:fixed; top:0px; left:0px; z-index:9999;" > I am jumping!</div>
confirm changes and press button "Open demo modal" after modal open, try mouse scroll. You will see, that our red block is jumping while scrolling.
Sometimes this effect continua after tm-modal was closed.
There is no this effect in Google chrome, but I see it on mobile browsers.