title: Change "drawingMode" in drawingManager of Google maps v3
body: <p>Look at this code:
  This is a Google tool that creates a panel on the map and helps us to draw shapes. By the <code>drawingMode: google.maps.drawing.OverlayType.CIRCLE</code> we can indicate that which tool was selected at the first load but I want to change it in the program. For example I want to change CIRCLE to POLYGON by clicking a button. How can I do something like this?</p>
  
  <pre><code>drawingManager = new google.maps.drawing.DrawingManager({
      drawingMode: google.maps.drawing.OverlayType.CIRCLE,
      drawingControl: true,
      drawingControlOptions: {
          position: google.maps.ControlPosition.TOP_CENTER,
          drawingModes: [google.maps.drawing.OverlayType.CIRCLE,
          google.maps.drawing.OverlayType.RECTANGLE,
          google.maps.drawing.OverlayType.POLYGON
          ]
      }
      });
  </code></pre>