NSTrackingAreaOptions.swift

public struct NSTrackingAreaOptions : OptionSetType {
    public init(rawValue: UInt)
    
    /* Type of tracking area.  You must specify one or more type from this list in the NSTrackingAreaOptions argument of -initWithRect:options:owner:userInfo: */
    public static var MouseEnteredAndExited: NSTrackingAreaOptions { get } // owner receives mouseEntered when mouse enters area, and mouseExited when mouse leaves area
    public static var MouseMoved: NSTrackingAreaOptions { get } // owner receives mouseMoved while mouse is within area.  Note that mouseMoved events do not contain userInfo
    public static var CursorUpdate: NSTrackingAreaOptions { get } // owner receives cursorUpdate when mouse enters area.  Cursor is set appropriately when mouse exits area
    
    /* When tracking area is active.  You must specify one of the following in the NSTrackingAreaOptions argument of -initWithRect:options:owner:userInfo: */
    public static var ActiveWhenFirstResponder: NSTrackingAreaOptions { get } // owner receives mouseEntered/Exited, mouseMoved, or cursorUpdate when view is first responder
    public static var ActiveInKeyWindow: NSTrackingAreaOptions { get } // owner receives mouseEntered/Exited, mouseMoved, or cursorUpdate when view is in key window
    public static var ActiveInActiveApp: NSTrackingAreaOptions { get } // owner receives mouseEntered/Exited, mouseMoved, or cursorUpdate when app is active
    public static var ActiveAlways: NSTrackingAreaOptions { get } // owner receives mouseEntered/Exited or mouseMoved regardless of activation.  Not supported for NSTrackingCursorUpdate.
    
    /* Behavior of tracking area.  These values are used in NSTrackingAreaOptions.  You may specify any number of the following in the NSTrackingAreaOptions argument of -initWithRect:options:owner:userInfo: */
    public static var AssumeInside: NSTrackingAreaOptions { get } // If set, generate mouseExited event when mouse leaves area (same as assumeInside argument in deprecated addTrackingRect:owner:userData:assumeInside:)
    public static var InVisibleRect: NSTrackingAreaOptions { get } // If set, tracking occurs in visibleRect of view and rect is ignored
    public static var EnabledDuringMouseDrag: NSTrackingAreaOptions { get } // If set, mouseEntered events will be generated as mouse is dragged.  If not set, mouseEntered events will be generated as mouse is moved, and on mouseUp after a drag.  mouseExited events are paired with mouseEntered events so their delivery is affected indirectly.  That is, if a mouseEntered event is generated and the mouse subsequently moves out of the trackingArea, a mouseExited event will be generated whether the mouse is being moved or dragged, independent of this flag.
}

Xcode7.1.1