typedef enum {XtCallbackNoList, XtCallbackHasNone, XtCallbackHasSome} XtCallbackStatus; XtCallbackStatus XtHasCallbacks(Widget _w, String _c_a_l_l_b_a_c_k___n_a_m_e);
If _c_a_l_l_b_a_c_k_s is not NULL, _X_t_C_a_l_l_C_a_l_l_b_a_c_k_L_i_s_t calls each of the callback procedures in the list, passing client data and _c_a_l_l___d_a_t_a. The _c_a_l_l_b_a_c_k_s parameter must specify the contents of a widget or object resource declared with representation type _X_t_R_C_a_l_l_b_a_c_k.
The _X_t_H_a_s_C_a_l_l_b_a_c_k_s function first checks to see if the widget has a callback list identified by callback_name. If the callback list does not exist, _X_t_H_a_s_C_a_l_l_b_a_c_k_s returns _X_t_C_a_l_l_b_a_c_k_N_o_L_i_s_t. If the callback list exists but is empty, it returns _X_t_C_a_l_l_b_a_c_k_H_a_s_N_o_n_e. If the callback list exists and has at least one callback registered, it returns _X_t_C_a_l_l_b_a_c_k_H_a_s_S_o_m_e.