private void formMouseDragged(java.awt.event.MouseEvent evt)//GEN-FIRST:event_formMouseDragged
    {//GEN-HEADEREND:event_formMouseDragged
        //if (evt.getButton() == MouseEvent.BUTTON1)
        {
            if (dc_selected != null && pres_point_dif != null && dc_selected.isEnterd(evt.getPoint()))
            {
                Point p = evt.getPoint();
                p.x = p.x - pres_point_dif.x;
                p.y = p.y - pres_point_dif.y;

                dc_selected.update_position(p);
            }
        }
        repaint();
    }//GEN-LAST:event_formMouseDragged