The effect of adjacent lines

The bottom black solid line going over Fitaly's bottom line, I think will always be there, making the bottom always a straight solid line.

The neighbor line at the upper border is not always there. It shows for example when the horizontal control bar is present if a file is wider than the screen.

When this upper line is present alternative 7 doesn't look as clean as 6 or 5.

I really like the cleaner look that alternative 5 has. My mind wants to reason that if a key has one round corner the other three corners should be round, at least a little bit. My eyes really like to look at version 5 much more than the other too. It has a certain soothing effect. If others feel the same way, I would dare to say it might minimize eye fatigue compared to the other two.

Emmanuel, I'm with you 100 percent on this one.

Anyone else?

I'm done,

Erwin