Disclosed are several methods, apparatus, and a system to create, expose, and hide embedded secondary content data relevant to a primary content page of an electronic book generated by a content generating device. The method, system, and apparatus is enabled through a Y-axis slide apart gesture that is applied to a notification region of the primary content page such that the secondary content data is made visible when the Y-axis slide apart gesture is applied to the notification region. The method, system, and apparatus is also enabled through a Y-axis pinch close gesture that is applied to a boundary of an exposed pane that is appearing in the primary content page such that the Y-axis pinch close gesture collapses the exposed pane in which the secondary content data is made visible. In one embodiment, the system comprises an association server, an electronic book distribution server, and a content rendering device.