As reported in email but added here so others can see the report and with more nuance.
I did some further testing.
The bad alignment only occurs when
If you Save or Save As and the dialog has been in the expanded mode, the panels are aligned fine.
I can reproduce this issue (essentially the column view on the expanded save dialog starts out scrolled to the right, and requires scrolling to the left to see the name column again); however I’m not sure it’s something that I have any control over 
McKinley runs as a sandboxed app, which means (among other things) that the save dialogs are owned and managed by the system. I get to give them a few views for drawing custom controls (such as the file format popup, or in some of the dialogs there are options controls below the file list). But Apple deliberately doesn’t let developers of sandboxed apps anywhere near the view that represents the list of files, for privacy reasons.
I’ll have a look to see if there’s anything odd I’m doing that is triggering this bug. I guess the next step is to see if it appears with a save dialog that has no customisation at all…
