**********************
|tool_image54| Polygon
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  Allow users to draw polygon as wish.  
  
Draw a polygon by freehand
===========================

  #. Select |tool_image54| tool; 
  
  #. Click the start point, move the pointer and a dash guideline appears.  Move it to desired position; 
  
  #. Click the second point, move the dash guideline to desired position again; 
  
  #. Do the same things as above till finish drawing a desired polygon.  
  
     |tool_image55|
	 
.. |tool_image54| image:: _static/tool_image54.png
.. |tool_image55| image:: _static/tool_image55.png