computing device associated with a first user. As discussed above, a multi-user sharing session might, for example, be implemented as a digital whiteboard presenting whiteboard objects. At operation 804, second content of a second section of the shared data unit is displayed on a display screen of a second computing device associated with a second user. 

[0078] The routine 800 proceeds to operation 806, where a request, for the second user to view the first content of the first section, is received from the first computing device. At operation 808, a user interface element is displayed on the display screen of the second computing device based on the reception of the request. The user interface element indicates that the second user has been requested to view the first content in the first section. 

[0079] The routine then proceeds to operation 810 where an indication that the user interface element has been selected is received. Based on receipt of the indication, at operation 812, the first content of the first section is displayed on the display screen of the second computing device. 

[0080] FIG. 9 shows additional details of an example computer architecture 900 for a computer, such as the client computing devices 104 and the server computer 112 shown in FIGS. 1A-1C, capable of executing the program components described herein. Thus, the computer architecture 900 illustrated in FIG. 9 illustrates an architecture for a server computer, a mobile phone, a PDA, a smart phone, a desktop computer, a netbook computer, a tablet computer, and/or a laptop computer. The computer architecture 900 may be utilized to execute any aspects of the software components presented herein. 

[0081] The computer architecture 900 illustrated in FIG. 9 includes a central processing unit 902 (“CPU”), a system memory 904, including a random access memory 906 (“RAM”) and a read-only memory (“ROM”) 908, and a system bus 910 that couples the memory 904 to the CPU 902. A basic input/output system containing the basic routines that help to transfer information between elements within the computer architecture 900, such as during startup, is stored in the ROM 908. The computer architecture 900 further includes a mass storage device 912 for storing an operating system 914, an application 916 such as a digital whiteboard application (e.g., with a feature to request attention), a shared data unit 110 containing content 106, and other data described herein. 

[0082] The mass storage device 912 is connected to the CPU 902 through a mass storage controller (not shown) connected to the bus 910. The mass storage device 912 and its associated computer-readable media provide non-volatile storage for the computer architecture 900. Although the description of computer-readable media contained herein refers to a mass storage device, such as a solid-state drive, a hard disk or a CD-ROM drive, 

