Window below the main tuning window

[Windows 10]

There is a rectangular window with a moving red line and a fixed green one below the main tuning window that I don't understand.  The red line sort of moves with the line in the main window but not exactly, so what is it for and what do the lines represent?

 

Thanks

[Jsalgado]

The green line represents the target note (which will be the one you need to reach in order to tune up your instrument), the red line represent the note you are playing at the moment. The idea is that both lines match, this is the indicator that your instrument is tune.

 

[Windows 10]

Quote

The green line represents the target note (which will be the one you need to reach in order to tune up your instrument), the red line represent the note you are playing at the moment. The idea is that both lines match, this is the indicator that your instrument is tune.

So there are two windows that do the same thing, is the smaller window more sensitive perhaps?

 

 

Edited July 13, 2017 by Windows 10
I think my quote from the earlier response was in a format that didn't indicate a question arising from the original response.