OK Walter

I was struggling to see your point.

The toolbox uses a clear X to let you know the string is nit played.

Your seeing the chart as where to place your fingers but seeing it ok to strum every one as there is no X

It would appear that strings to be played open have the blue circle as an indicator.

In A maj and C maj there is no blue circle on the 6th string so it is not to be played.

Only strum a red for a fret or blue for open

Just how your seeing it I think

Dave