There is also a beautiful reason. If the handle of the pointer is designed to be centrosymmetric, the inclination of the handle is 22.5 degrees, and the tan value of 22.5 degrees is about 0.41, which means that when the handle is drawn, every pixel moved horizontally will be drawn down by 2-3 pixels. Early mouse icons were not anti aliased, just monochrome icons, so the edges of the handle would be uneven and ugly. When it is designed to be 26.57 degrees, Tan value is just 0.5. When the handle is moved 1 pixel horizontally, it can be fixed to draw 2 pixels down, and the edge will be better.