I have a table like the one below. Is it possible to highlight an
offset cell depending upon which cell is currently selected? In other
words, if I click on cell A1, can the background color of cell D1
change to say yellow. Conversely, if I click on cell D1 I would want
the background color of cell A1 to change. Any ideas? Thanks in
advance.

A B C D E F
1 a b c 1 2 3
2 d e f 4 5 6
3 g h i 7 8 9