Dirdiff is a graphical tool for displaying the differences between
directory trees and for merging changes from one tree into another.
Dirdiff can handle up to five trees. It displays a main window with a
list of the files that are different between the trees with colored
squares to indicate the relative ages of the versions. A menu allows
you to display the differences between any two of the versions in
another window. Another menu allows you to copy the file from one tree
to another.