becomes nonzero (observed value: 1) when the camera is in record mode and either of the following conditions is true
- shooting menu is shown (the one you activate with the func/set button)
- AEL (exposure lock) or AFL (AF lock) is active
- maybe when other similar Canon function is active (for example FE lock)
Default CHDK action (as of r1997): OSD will vanish when this becomes nonzero. If this is undesired, CAM_SHOW_OSD_IN_SHOOT_MENU needs to be defined in the camera's platform_camera.h.