func LineStipple(factor int32, pattern uint16) {
	syscall.Syscall(gpLineStipple, 2, uintptr(factor), uintptr(pattern), 0)
}
func LineStipple(factor int32, pattern uint16) {
	syscall.Syscall(gpLineStipple, 2, uintptr(factor), uintptr(pattern), 0)
}
// specify the line stipple pattern