[CentOS] Percent bar on screen - for 2 seconds

Sat Aug 8 01:12:14 UTC 2015
Marko Vojinovic <vvmarko at gmail.com>

On Sat, 08 Aug 2015 00:07:35 +0000 (GMT)
Wes James <comptekki at me.com> wrote:

> Every once in awhile I see this horizontal percent bar flash up on
> the screen then disappear.  What is that?
> 
> CentOS 7.1,  kde.

Is it a laptop, running on batteries?

I have a configuration with a laptop with an external monitor attached,
while the laptop's monitor is off. When the laptop is running on
batteries (don't ask me why), the system power manager tries to
readjust the screen brightness (I guess in order to honor
the power settings in KDE), fails (since LVDS is off, or since VGA
doesn't support brightness changes, or otherwise), then tries again a
few minutes later, repeatedly. Once AC power is turned on, it stops
trying.

The horizontal percent bar flashing up is a notification of the
brightness level changing, during each power manager's attempt at it.

If you use the appropriate keyboard control combination on the laptop
to change the screen brightness, you can probably trigger the percent
bar manually. It is similar to changing the audio volume, and other
percentage bars.

This hasn't annoyed me enough (yet) to get me to look into what's
causing it or how to fix it. It doesn't happen when the laptop is on
AC power. It might be a simple matter of configuring it appropriately in
systemsettings power management controls, but I never bothered...

Or maybe your problem is caused by something else... :-)

HTH, :-)
Marko