add: if (count == 0) return NULL;
context: WWindow *wSwitchPanelSelectNext(WSwitchPanel *panel, int back){  WWindow *wwin;  int count = WMGetArrayItemCount(panel->windows);  if (panel->win)    changeImage(panel, panel->current, 0);    if (!back)    panel->current = (count + panel->current - 1) % count;  else    panel->current = (panel->current + 1) % count;  wwin = WMGetFromArray(panel->windows, panel->current);  if (panel->win) {    WMSetLabelText(panel->label, wwin->frame->title);    changeImage(panel, panel->current, 1);  }  return wwin;}