this.selectBlob = function(x, y)
      {
        var i, minDist = 10000.0; 
        var otherPointMass; 
        var selectedBlob; 
        var selectOffset = null; 
        
        if(this.selectedBlob != null)
        {
          return; 
        }
        
        for(i = 0; i < this.blobs.length; i++)
        {
          if(this.blobs[i] == null)
          {
            continue; 
          }
          
          otherPointMass = this.blobs[i].getMiddlePointMass(); 
          aXbX = x - otherPointMass.getXPos(); 
          aYbY = y - otherPointMass.getYPos(); 
          dist = aXbX * aXbX + aYbY * aYbY; 
          if(dist < minDist)
          {
            minDist = dist; 
            if(dist < this.blobs[i].getRadius() * 0.5)
            {
              this.selectedBlob = this.blobs[i]; 
              selectOffset = { x : aXbX, y : aYbY };  
            }
          }
        }
        
        if(this.selectedBlob != null)
        {
          this.selectedBlob.setSelected(true); 
        }
        return selectOffset; 
      }