When we want only use the keyboard on Nautilus and we want to select non-consecutive files and folders, we cannot see that files has the focus.
Holding down the Ctrl key, we can moving through the files and folder with the Arrows key, but only when we hit Space key, we realize where we are.
This becomes a bigger problem when there are many files and folders and we have to hitting the arrow key very quickly.
This problem happen in Ambiance Theme, only in High Contrast Theme it works well.
In High Contrast Theme you can see that Template folder has the focus
It is in Ambiance Theme(default), the Template folder has the focus, nevertheless it is impossible to know.