Right-click on the white background of your Explorer window. Click BK Diff Directory...

This will bring up the BK difftool that shows us side-by-side differences in BitKeeper-controlled files. It will load showing the first changed file and centered on the first change in that file. Like this:

So, where did foo.c go?! Well, BitKeeper doesn't know anything about foo.c so there's nothing to diff. Don't worry though. When it comes time to commit, BitKeeper will tell us there is an extra file there it doesn't know about and give us the option to include it then.