1866d628_Appendix_B__X_Config_Options__Equipment
[Value] 2 [Equipment] 
"Blueline" glasses. These usually involve a passthrough cable between the monitor and graphics card. The glasses know which eye to display based on the length of a blue line visible at the bottom of the screen. When in this mode, the root window dimensions are one pixel shorter in the Y dimension than requested. This mode does not work with virtual root window sizes larger than the visible root window size (desktop panning). This mode is not available on G8xGL and higher GPUs.
Appendix B. X Config Options