XSetDeviceValuators() - initialize the valuators on an extension input device
XSetDeviceValuators (Display *display, XDevice *device,
int *valuators, int first_valuator,
int num_valuators)
The XSetDeviceValuators(3) request sets the current values of the valuators of an input device. The valuators in the range first_valuator to (first_valuator + num_valuators) are set to the specified values. Valuators are numbered beginning with 0. Not all input devices support initialization of valuator values. If this request is made to a device that does not support valuators initialization, a BadMatch error will occur.
If the request succeeds, a status of Success is returned. If another client has the device grabbed, a status of AlreadyGrabbed is returned.
XSetDeviceValuators(3) can generate a BadLength, BadDevice , BadMatch, or BadValue error.
Programming With Xlib