In Firefox, if you do a search (find-in-page), the browser will add lines to the scrollbar for each search-result found to make it easier to see how many search-results there are and where in the page they are located, as seen in the screenshot.
Is this only part of the browser, or is it achievable by a webpage (CSS/JavaScript)? All I can find is information about generic customization of size and shape of the scrollbar, not about marks in the scrollbar.
