MouseButtonFuncType button_callback = top->get_mouse_button_callback();
if(button_callback && (bnstate != prev_state)) {
int num_bits = sizeof bnstate * CHAR_BIT;
MouseButtonFuncType button_callback = top->get_mouse_button_callback();
if(button_callback && (bnstate != prev_state)) {
int num_bits = sizeof bnstate * CHAR_BIT;