Tearing with 8600GTS, 256.35, xine-lib-1.2 when avoiding XLockDisplay()
xine-lib's video_out_vdpau.c uses XLockDisplay() when calling VDPAU functions. This is due to some issues caused by xine-ui. I was trying to fix those xine-ui issues so that these XLockDisplay() calls can be avoided (these calls synchronize decoding and displaying and may be the reason for some other issues).
After fixing the issues and disabling those XLockDisplay() calls, tearing appeared. Reenabling the XLockDisplay() calls removed tearing again.