server_client_get_client_window
cw = server_client_get_client_window(tc, w);
cw = server_client_get_client_window(loop, w->id);
cw = server_client_get_client_window(loop, w->id);
cw = server_client_get_client_window(c, id);
cw = server_client_get_client_window(c, s->curw->window->id);
cw = server_client_get_client_window(c, w->id);
struct client_window *server_client_get_client_window(struct client *, u_int);