In the second variant I have shown here the error is: commander. cc: In function 'void begin_collect_data (GtkObject*)': commander. cc: 92: error: invalid cast from type 'void*' to type 'drawing_area' which is really no surprise because I am trying to cast a pointer to a non-pointer.
/ * Called when a process monitor fires * / void (* stop_select) (ErlDrvEvent event, void* reserved);
The driver interface function void stop_select (ErlDrvEvent event, void* reserved) driver_select when it is safe to close an event object.