I've been seen some screen switching issues as noted in EAB forum: http://eab.abime.net/showthread.php?t=105576&page=20. I had some issue with CVisionPPC and PIV (as well as CVisionPPC and ZZ9000) but to remove any complications of the CVisoinPPC or ZZ9000, I did a comparison by only installing a CVision64 and a PIV card in my A4000T (all other graphic cards removed -- no CVIsionPPC installed and no ZZ9000). DISPLAYCHAIN=YES for PIV and DISPLAYCHAIN=NO for CV64. Then I did these experiments. This is not hitting exactly the same kind of case for the other combos but I do see issue in 1 case:
Note that WB=workbench screen
1) WB CV64 screen --> create PIV RTG screen. Good swapping back and forth between screens
2) WB PIV screen --> create CV64 RTG screen. Good swapping back and forth between screens
3) WB CV64 screen --> create Hires Laced. 1st time swap, flickerfixer on PIV output good. On 2nd and subsequent times, no flickerfixer output on PIV (black). If I again create PIV RTG, and then do Hires laced, it recovers first time and I see flickerfixer output. Subsequent times no flickerfixer output.
4) WB CV64 screen, keep a 2nd PIV RTG screen open, then open up a 3rd HiresLaced screen. I can swap back and forth between them and all is okay.
As mentioned in EAB forum Thor has an idea and can give a beta for me to check but need approval of my purchase.