WKNavigationAction

/*! @abstract The frame requesting the navigation.
 */
@property (nonatomic, readonly, copy) WKFrameInfo *sourceFrame;

/*! @abstract The target frame, or nil if this is a new window navigation.
 */
@property (nullable, nonatomic, readonly, copy) WKFrameInfo *targetFrame;

/*! @abstract The type of action that triggered the navigation.
 @discussion The value is one of the constants of the enumerated type WKNavigationType.
 */
@property (nonatomic, readonly) WKNavigationType navigationType;

/*! @abstract The navigation's request.
 */
@property (nonatomic, readonly, copy) NSURLRequest *request;
property (nonatomic, readonly) NSEventModifierFlags modifierFlags;

/*! @abstract The number of the mouse button causing the navigation to be requested.
 */
@property (nonatomic, readonly) NSInteger buttonNumber;