How to compare newest commit to oldest commit in gitk

When I do gitk --follow <filename>, the left pane lists all the commits of the given filename.

If I click one of those commits, the bottom-left pane (just below the commit/branch/tag list), shows a diff between this selected commit and the previous one.

Is there a way to tell gitk to show a diff between this selected commi开发者_如何转开发t and the oldest commit? (i.e. the one at the bottom of the list)

Select the new commit, then right-click the old commit (without selecting it first) and choose "Diff this -> selected".