[gurkendoktor]

I had always assumed that SourceTree was a portable Qt app (it looks like it, doesn't it?), but it's only available on macOS and Windows.

Tower and GitUp are a huge lock-in into macOS for me. Tower for line-by-line staging/discarding, GitUp for minor history fix-ups (editing a commit message without remembering the CLI command, etc.).

[iamthad]

For what it's worth, git add, git checkout, and git reset all take the -p (or --patch) option, which allows selection of sub-sections of files to stage, discard, or unstage, respectively.