Full thead detailing reasons and implementations in-depth: https://discuss.kde.org/t/improvements-to-autoscrolling-middle-click-and-drag-to-scroll/34011/1 Split from this issue: https://bugs.kde.org/show_bug.cgi?id=503998 as per cwo's suggestion. Autoscrolling / On-button-scrolling / "Hold middle click and move mouse to scroll" feature from the mouse settings menu needs a way to be turned off in specific windows/applications, in which it may conflict with the program's own middle click behavior.
*** Bug 504133 has been marked as a duplicate of this bug. ***