What does "Show tab list menu" do?

[ivancho-kun]

Sorry we changed it intendedly.
Don't you think it is more reasonable?

I really don't. I think it's more individual. The Standard tab order on the left side was more intuitive for me (pic). Maybe it could be the solution to add checkboxes in the menu settings (or active arrows on the tab lists) for changing this order. Think about this, please