The expvis flag will change the number of visual instances in the following visual groups:
8-bit PseudoColor Overlay
24-bit Non-linear TrueColor
24-bit Linear TrueColor
The number of instances that expvis will alter depends on whether the monitor is in monoscopic or stereoscopic resolution. In monoscopic resolution, if expvis is enabled, the order of the screen visual groups will be preserved, but within each group mentioned above, a "double-buffer capable" visual instance will be added. In stereoscopic resolution, two additional visual instances: "double-buffer, stereo capable" and "single-buffer, stereo capable", will be added. The "double-buffer capable" visual instances, if present, will always come ahead of the "single-buffer capable" visual instances, and the monoscopic visual instances will always come ahead of the stereoscopic ones.
For example, if you specify the following in stereoscopic resolution:
ffbconfig -overlayorder first -expvis enable
the screen visual list will be:
8-bit PseudoColor Overlay (Mono, Stereo)
8-bit PseudoColor (DB Mono, SB Mono, DB Stereo, SB Stereo)
8-bit Miscellaneous (StaticColor, Non-linear StaticGray... etc)
8-bit Linear StaticGray
24-bit Linear TrueColor (DB Mono, SB Mono, DB Stereo, SB Stereo)
24-bit Non-linear TrueColor (DB Mono, SB Mono, DB Stereo, SB Stereo)
24-bit DirectColor (DB Mono, SB Mono, DB Stereo, SB Stereo)
There is no double-buffer capable overlay visual instance.