title: Drawing lines by dragging the mouse in matlab
body: <p>I want to draw a set of disconnected lines on top of an image by dragging the mouse while pressing the left button. However, if I click on a previously drawn line to specify the starting point of the next line, the callback function is not being called and I don't get the point. Here is my code: </p>
  
  <pre><code>function main_test
  
  S.fH = figure('menubar','none');
  im = imread( 'image.jpg' );
  
  S.aH = axes;
  S.iH = imshow( im ); hold on
  axis image;
  
  X = [];
  Y = [];
  
  set(S.aH,'ButtonDownFcn',@startDragFcn)
  set(S.iH,'ButtonDownFcn',@startDragFcn)
  set(S.fH, 'WindowButtonUpFcn', @stopDragFcn);
  
  function startDragFcn(varargin)
      set( S.fH, 'WindowButtonMotionFcn', @draggingFcn );
      pt = get(S.aH, 'CurrentPoint');
      x = pt(1,1);
      y = pt(1,2);
      X = x;
      Y = y;
  end
  
  function draggingFcn(varargin)
      pt = get(S.aH, 'CurrentPoint');
      x = pt(1,1);
      y = pt(1,2);
      X = [X x];
      Y = [Y y];
  
      plot(X, Y, 'r', 'LineWidth', 6);
      hold on
      drawnow 
  end
  
  function stopDragFcn(varargin)
      set(S.fH, 'WindowButtonMotionFcn', '');  %eliminate fcn on release
  end
  
  end
  </code></pre>
  
  <p>Would you please help me to identify the problem in this. </p>
  
  <p>Thank you in a advance..</p>
  
  <p>cheers, 
  Sawsan</p>