extern void focus(Client *c); /* focus c, c may be NULL */
extern void focusnext(Arg *arg); /* focuses next visible client, arg is ignored */
extern void focusprev(Arg *arg); /* focuses previous visible client, arg is ignored */
extern void focus(Client *c); /* focus c, c may be NULL */
extern void focusnext(Arg *arg); /* focuses next visible client, arg is ignored */
extern void focusprev(Arg *arg); /* focuses previous visible client, arg is ignored */