A device for operating a computer mouse has improved multi-axes mounting to the arm of a desk chair. The device comprises a platform with a holding area for the computer mouse. The platform should be sufficiently sized for a computer operator's forearm to rest thereon. The improved mounting for this device includes a rod from which at least two brackets are connected. One bracket rotatably connects to this rod and the other bracket slidably connects to same. Preferably, a braking mechanism prevents the platform from being rotated too far about the chair arm and dumping all holding area contents.