Until implemented in the Log window, you may use the Working Tree window which supports showing the files non-recursively.

Double-click in the Files view also invokes Show Changes. Because the File compare tools only support files, it needs to be triggered on the file level, not on the commit level.

Is the current bold text not easy to spot?

In SmartGit you don't need to drag/drop to see a diff. Just select the 2 commits you want to diff. Then open the external file compare from the changed files in the Files view.

You can already right-click a repository and open a Git shell (or Terminal depending on the platform) where you can invoke the Git commands.

In the next 20.1 build "Nautilus" will be replaced with "Files (Nautilus)".

Starting with SmartGit 19.2 preview build 15043 you can customize the low-level property

log.details.headerValueSeparator

to replace the newline character with, e.g. spaces.

When exactly the search and replace should be triggered? Please take a look at the current Add Tag dialog and press Ctrl+Space - do you want to get something similar for the Add Branch dialog?

No, just one option was added in 19.2 to switch between mixed file display and working tree + index files. Because of lack of better matching options I mark this request as completed.