ShowHideCursor
par->riva.ShowHideCursor(&par->riva, 0);
par->riva.ShowHideCursor(&par->riva, 1);
chip->ShowHideCursor = ShowHideCursor;
chip->ShowHideCursor = ShowHideCursor;
chip->ShowHideCursor = ShowHideCursor;
int (*ShowHideCursor)(struct _riva_hw_inst *,int);