Martin Baehr wrote:
--first-parent seems to only reduce part of the history of merges but not collapse all linear sequences of commits. (only commits that have more than one parent or child should be shown.)
I see what you mean. Wouldn't know the magic incantations for that, not quite sure if it's not possible though, try "man git-rev-list". If you can get "git log" or "git rev-list" to show the relevant commits, then the same arguments supplied to gitk will give the same treeview.
In any case, the tags like 7.1 7.3 7.5 allow you to jump to the right spot in gitk.