 }
 
 extension Drop {
-    private class func window() -> UIWindow {
-        return UIApplication.sharedApplication().keyWindow!
-    }
-    
     private class func statusBarHeight() -> CGFloat {
         return UIApplication.sharedApplication().statusBarFrame.size.height
     }

    private class func down(status: String, state: DropStatable?, blur: DropBlur?) {
        self.upAll()
        let drop = Drop(frame: CGRectZero)
        Drop.window().addSubview(drop)
        
        let sideConstraints = ([.Left, .Right] as [NSLayoutAttribute]).map {
            return NSLayoutConstraint(
                item: drop,
                attribute: $0,
                relatedBy: .Equal,
                toItem: Drop.window(),
                attribute: $0,
                multiplier: 1.0,
                constant: 0.0

    }
    
    public class func upAll() {
        guard let window = UIApplication.sharedApplication().keyWindow else { return }
        for view in window.subviews {
            if let drop = view as? Drop {
                drop.up()
            }
