Robert, please give the latest 8.1 preview a try. It's not what you are asking, but maybe helps a step forward.

I've created a git-changelog.sh with following content:

#!/bin/bash
git log --pretty=oneline $1..$2 > $3

and configured it in SmartGit:

Most likely this task best is suited for using a script to be integrated into SmartGit as external tool.

See http://smartgit.userecho.com/topics/43-true-dark-color-mode/

Please try Help | Check for Latest Build in the SmartGit 8.1 preview

You already can select the commits and select Copy Message in SmartGit 8.1.

Why you are not using a plain compare (F4)?