add property 'blurSuperView'

Hi, I use this in my component which is a custom alert view.
And my problem is,  when I show the alert view, actually it was created on another window.
Therefore I add a new property `blurSuperView`. When `refresh` been call, it check if blurSuperView had been set to other view. if not, use superview as backgroundView.

Hope this is useful for others.