This addon was developed using XF 2.0.12. It's designed to replace the native scroll buttons with more versatile and better functioning buttons.
When you are at the top of a scrollable page, only the "scroll to bottom" button appears:
When you are somewhere in the middle, both buttons appear:
And, when you're at the bottom of the page, only the "scroll to top" button appears:
Users on mobile devices will see the buttons at the bottom of the screen, full width:
If a page is not scrollable but the browser window is resized such that the vertical scrollbar appears, then the buttons will also appear.
The buttons are fully customizable per style:
To install, download the attached .ZIP file to your local media, extract the contents, and upload the contents of the "upload" folder to your forum's root.
Then, for each style you wish to use this addon, turn off the native scroll buttons, and set this addon to be active in that style.