I’d like to be able to browse all the files in a git repository as they exist at a given commit.

Use cases:
• I added a new file to branch A. I want to add that file to branch B.
• I want to see how a file changed between commit C and D, so I want to extract the individual files to a separate location (Save As… dialog). Note that the file did not necessarily change in either C or D.
• Like the previous one, but maybe a whole folder of files.
• I want to run blame on a specific file.
• And many more.

From the command line, I can use one of the many increasingly prolific variants of `git checkout` to do the first two (not sure if it handles folders). I don’t think SourceTree has a way to browse or perform commands on arbitrary files in a repository. I think the best answer is to browse through the commit history until you happen to find the right file.