A Pixel Grid Favored a Slanted Arrow
A screen does not draw a pointer as a smooth line. It lights a pattern of tiny square pixels. When computer mice first appeared, displays had relatively few pixels, so a small cursor had to make its shape clear with a very limited number of squares.
A straight-up arrow could look cramped or lose its outline at that size. Tilting the arrow let its shaft and triangular tip form a more recognizable shape on the pixel grid. The familiar pointer was designed for those practical display limits, not because the mouse itself moved at an angle.
The Tilt Became a Lasting Convention
The pointer’s angled shape also makes its tip easy to distinguish from the broader body. That matters because the tip marks the precise spot where a click will land. The cursor can be tilted while still pointing accurately: its active point is at the sharp end, not at the center of the arrow.
Modern screens can render a straight arrow easily, but changing a symbol people have learned to recognize would bring little benefit. The slant is a small piece of early interface design that survived long after the pixel constraints that helped shape it faded.
