Windows Explorer Display

When I use Windows Explorer the +/- boxes which allow me to expand or collapse a branch are displayed correctly. Until (very) recently these boxes were connected by the appropriate vertical and horizontal rules, making it easy to follow each branch to as many layers depth as necessary.


Now those lines have disappeared and there appears to be no way to get them back.

Any ideas?

 

Many thanks! That did the trick. Just curious as to why that switch had got changed, certainly I had not had need to check the Folder Options for many months until this issue occurred.