private @Nullable TabLabel findLabel(Point dragPoint) {
    final Component at = tabs.findComponentAt(dragPoint);
    if (at instanceof InplaceButton) return null;
    final TabLabel label = findLabel(at);

    return label != null && label.getParent() == tabs && label.getInfo() != dragSource ? label : null;

  }
private @Nullable TabLabel findLabel(Point dragPoint)