Yes, there are official instructions in the docs.
In practice, I find this workflow useful:
- Right click a file you want to partially commit
- Click Restore after commit - This immediately creates an internal copy of the file.
- Double click the file to edit in TortoiseGitMerge
- Right click -> Mark this block for each change you want to commit now
- Right click -> Leave only marked blocks to revert the other changes.
As an alternative to these two steps, you can edit the file the way you want.
- Save and Close TortoiseGitMerge
- Commit - this restores the internal copy of the file afterwards.
- The changes you just reverted in TortoiseGitMerge are now restored in your working tree.
