1. One or more computer storage media devices having stored thereon multiple instructions that, when executed by one or more processors of a device, cause the one or more processors to: display, in each of two display areas, different pages of a digital book using a book display model; display, in response to a request to semantically zoom out, the digital book in a broader context, the broader context using a context display model rather than the book display model; display, in response to a request to semantically zoom in, the digital book in the book display model rather than the context display model; receive a request to enter a scratchpad mode, and in response to the request: automatically combine the different pages of the digital book displayed in each of the two display areas for display in a first of the two display areas and clear at least a portion of a second of the two display areas; display, in the first of the two display areas, the combined different pages of the digital book that were previously displayed in both of the two display areas; and display, in the second of the two display areas, a collection of pages of the digital book that have been moved by a user of the device from the first of the two display areas to the second of the two display areas.
1. One or more computer storage media devices having stored thereon multiple instructions that, when executed by one or more processors of a device, cause the one or more processors to: display, in each of two display areas, different pages of a digital book using a book display model; display, in response to a request to semantically zoom out, the digital book in a broader context, the broader context using a context display model rather than the book display model; display, in response to a request to semantically zoom in, the digital book in the book display model rather than the context display model; receive a request to enter a scratchpad mode, and in response to the request: automatically combine the different pages of the digital book displayed in each of the two display areas for display in a first of the two display areas and clear at least a portion of a second of the two display areas; display, in the first of the two display areas, the combined different pages of the digital book that were previously displayed in both of the two display areas; and display, in the second of the two display areas, a collection of pages of the digital book that have been moved by a user of the device from the first of the two display areas to the second of the two display areas. 4. One or more computer storage media devices as recited in claim 1 , wherein to display the digital book in the broader context is to display both a first page of the digital book and one or more pages preceding the first page in a first display area of the two display areas, and display both a second page of the digital book and one or more pages following the second page in a second display area of the two display areas.