Total Commander

Options \ Operation \ Edit/View.
It seems that once upon a time there was a frame around some controls. Then controls were gone but the frame remains.
In 32-bit version:
Image: https://s8.hostingkartinok.com/uploads/images/2019/01/12f306d3462199773463aa42f66025f2.jpg
In 64-bit version:
Image: https://s8.hostingkartinok.com/uploads/images/2019/01/4cf2fcf0171fc7ef921ef428f618dcf1.jpg
TC 9.20b6

They aren't group frames, they should just be vertical lines separating the left and right half of the frame. They look OK here when not using classic theme.