Running Leap 42.2 with KDE with dual monitors and an optical mouse.
My mouse refused to behave. The drag was extremely slow and the mouse pointer would not hover correctly over click positions. Changing the mouse config settings made no difference. After much tearing of hair and gnashing of teeth and time researching the net I discovered by accident that it was the shiny smooth surface of the desk. A mouse mat solved the issue even though an optical mouse does not require one. This is the first time I have seen this problem in 20 years of IT.