[mythtv-users] NVCtrl: The NV-CONTROL X extension is not available on screen 0 of ''

[John Pilkington]

I'm getting that 'Info' message on startup of mythfrontend, 2019-render 
branch, in my el7 box that has no nVidia hardware.  Another box, Fedora 
30 with nVidia hardware is fine.

libXNVctrl version 352.21-2 is installed.  The codes of NVCtrl.h for el7 
and f30 are identical.

I'm trying to track down a slow drift in a/v sync that I don't see on 
other boxes, and this looks a vaguely plausible candidate.  I don't know 
if the empty quotes are the problem or if it's something else.

2019-11-29 22:31:22.691461 I  DispResX: Raw/unsorted XRANDR modes:
2019-11-29 22:31:22.691489 I  1440x900  75.00   60.00

$ xrandr
Screen 0: minimum 8 x 8, current 1440 x 900, maximum 32767 x 32767
VGA1 connected primary 1440x900+0+0 (normal left inverted right x axis y 
axis) 410mm x 260mm
    1440x900      59.89*+  74.98

$  mythfrontend -display VGA1 -v playback
qt.qpa.screen: QXcbConnection: Could not connect to display VGA1
Could not connect to any X display.

Any ideas?  Thanks,

John P