red horizontal line on audio tracks

After I recored some tracks I closed the project and re-opened it some days later.
In the editor I switched from “stacked” to “overlaid” layer mode.
And suddenly each track my mouse cursor hovers over get’s a red horizontal line (in 2/3 of it’s height). Is this a bug or a feature I can turn off?

can you take a screenshot and post it somewhere? e.g. or zimage

what version of ardour, on what platform?
There are red lines on the tracks I hovered over and no red lines on the tracks I didn’t hover over with the mouse. I use Ardour 5.12 on Linux Mint 18.2 64 bit.

That is probably the “region gain line” which can be used to adjust the loudness of the region. Normally it’s a green line, but it looks like you are running a different “theme”.

You can use the “Draw” tool to adjust the line control-points inside the region.

Please switch back (temporarily) to the default (“dark”) theme and re-take that screenshot. Also, if you’re in timezone within a few hours of UTC-5, it will likely be quicker to resolve this on IRC rather than via a web forum.