code: private double calculateBufferFromPixelTolerance() {
  
  		Coordinate c1 = mapPresenter.getViewPort().getTransformationService()
  				.transform(new Coordinate(0, 0), RenderSpace.SCREEN, RenderSpace.WORLD);
  		Coordinate c2 = mapPresenter.getViewPort().getTransformationService()
  				.transform(new Coordinate(pixelBuffer, 0), RenderSpace.SCREEN, RenderSpace.WORLD);
  		return c1.distance(c2);
  
  	}
docs: Calculate a buffer in which the listener may include the features from the map.
  
  @return double buffer