Show diffs in submodules

[lainegates]

Describe the bug
This may not be a bug. But it doesnot work as expected.
git diff shows code changes, but git ui does not display git diff information

To Reproduce
I am working in a git repo with submodule.
I read submodule git diff from main git repo, gitui found the diff, but doesnot display it.

Expected behavior
gitui show git diff for each file.

Screenshots

Context (please complete the following information):

• OS/Distro macOS 10.15.5
• GitUI Version 0.26.3