         }
     }
     
+    /// Whether to draw a border on the blur view.
     var drawsBorder = false {
         didSet {
             if drawsBorder != oldValue {

            }
        }
    }

    override var annotationFrame: CGRect? {
        return annotation?.frame
    }
    
    var touchTargetFrame: CGRect? {
        guard let annotationFrame = annotationFrame else { return nil }
        
        let size = frame.size


    // MARK: - Properties

    private let EAGLContext: OpenGLES.EAGLContext
    private let GLKView: GLKit.GLKView
    private let CIContext: CoreImage.CIContext

    /// The corresponding annotation.
    var annotation: BlurAnnotation? {
        didSet {
            setNeedsDisplay()
