public extrusionElt()
 {
     _ext = skewEltExt.view;
     _type = extrusionEltType.parallel;
     _render = extrusionEltRender.solid;
     _plane = extrusionEltPlane.XY;
 }
 public extrusionElt()
 {
     this.extField = skewEltExt.view;
     this.typeField = extrusionEltType.parallel;
     this.renderField = extrusionEltRender.solid;
     this.planeField = extrusionEltPlane.XY;
 }