What happens when you overengineer a simple scroll bar on Scratch? How good can it be? This project is a recreation of scrollbar on google.com?q=... (with dark mode) and features scroll arrows, mouse movement responsiveness and scrolling when holding mouse above and below the bar and of course the detection of mouse scroll. Check it out, compare it to google's and use for your needs (if you aren't scared of the amount of bonus blocks it will add to your project). Look into BAR sprite, it has all settings for its corresponding bar (either vertical or horizontal). Please leave a credit if you do use it.
Based on google.com/search?q=... scroll bar (dark mode) (at least in Chrome on windows it looks this way) Please leave a credit if you use it.