public boolean addSlot(boolean right,int slot){
  if (!active || right != this.right) {
    return false;
  }
 else   if (slots.contains(slot)) {
    return false;
  }
 else {
    slots.add(slot);
    return true;
  }
}

public boolean addSlot ( boolean right , int slot ) { if ( ! active || right != this . right ) { return false ; } else if ( slots . contains ( slot ) ) { return false ; } else { slots . add ( slot ) ; return true ; } }
add a slot to an in - progress drag operation if possible .
