add: if (CheckCameraOpen() == FALSE) return FALSE;
context: gboolean change_camera_settings(GtkWidget *widget, GdkEvent *event, gpointer data){  if(sizeof original_usp != 0x804 || !get_usp_file(&original_usp)){    return FALSE; // is anybody checking this???  }  char *msg = verify_usp_data(&original_usp.data);  if(msg){    fprintf(stderr, "ERROR: %s\n", msg);    return FALSE;  }  memcpy(&current_usp, &original_usp, sizeof original_usp);  memcpy(&default_usp, &original_usp, sizeof original_usp);  default_usp.data.fps = 30;  default_usp.data.hardlimit = 25;  default_usp.data.softlimit = 20;  default_usp.data.xres = cpu_to_le16(320);  default_usp.data.yres = cpu_to_le16(240);  if(!SettingsDialog(&original_usp.data))    return FALSE;  fprintf(stderr, "notice: called SettingsDialog and returned\n");  return TRUE; // success}