Now that you've helpfully explained where I can actually see the whole set of staged items, I found that the LEFT view in the diff view, in this mode, does have "Unstage hunk" on the menu.   That's a little weird, but also logical I guess.  All good.  There's all the features I expect, just seemingly well hidden away.

I'm using the latest on the website as of yesterday 19.1.6 #14220

I see now there is an "Index (1 change)" node in the tree, which, when selected, despite the file status showing "Staged, modified" as it does when the "Working tree" item is selected, it does only show the staged changes at that time.  Very subtle.  I've never seen the tree used in this way, but I guess it makes sense once you understand that it is there -- and I did search fairly hard, I thought, for this feature yesterday.

Thanks for the link.  I was able to download a LibreOffice .oxt file - figure out it's just a .zip file, and pull out the en_GB.dic from there.  smartgit didn't appear to recognise it or use it until I actually removed the en_US diictionary.   Anyway, this is great now.  Thanks.

I believe I am looking at "full file contents".  I can scroll through the full file.  But I see no option to revert.  The popup menu, where I expected "revert hunk" may lie, shows nothing like this.  Could you elaborate?

Could you elaborate?  Because I cuoldn't find it.  I did try.  The reply isn't particularly helpful.  What is "the index node" ?

This reply is somewhat condescending.  The UI appears to show just "Chinese" and "English" options.  A bit more digging around today shows that .indeed "en_US" is the only dictionary provided - in /usr/share/smartgit/dictionaries/en_US.dic - so where might I get other .dic files?