Some laptops such as the Lenovo ThinkPad series and many Dell Business laptops have a little joystick mouse integrated on their keyboard. I am not sure what it's general name is but I have heard some people call it a nipple mouse.
Below the spacebar on such laptops, there are with three buttons; two for left/right click and a center button, which, if depressed while scrollable documents are focused onscreen, will scroll the doc up or down depending on how you pull on the joystick on the keyboard.
Vertical scrolling in such a manner works fine in Spotify but for some reason horizontal scrolling does not. I have been able to replicate this on every laptop with this kind of pointing device.
It's not a big issue but it's incredibly annoying.
I am not sure how hard it would be to implement; it could take just a few lines or it could be be a driver issue.
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