b9fdba7ff8
This adds a context-menu command to put a mark on this commit. There is at most one marked commit at any time, and it is indicated by a box drawn around the headline. Once a commit is marked, two other context-menu commands become available: one to select the marked commit, and another to find the closest common descendant of this commit and the marked commit. The "find common descendant" command uses the displayed parent/child relationships (i.e. the rewritten parent pointers produced by git log), not the real parent/child relationships. Currently the UI will be unresponsive while gitk is working out the nearest common descendant; this should be improved in future. Signed-off-by: Paul Mackerras <paulus@samba.org>