For consistency with other Windows programs, the keyboard shortcut Ctrl-+ should also do the same thing.
I notice something has been implemented for this in one of the recent releases, but it doesn't do the same thing as selecting "Auto Size All Columns". I think it's a useful addition, but currently there are a few problems:
1. The highlight column becomes really wide (for me at least, as I prefer it to be a narrow "strip" rather than a thick block)
2. Genre doesn't appear to reflect the width of its contents at all
3. The rating column seems to always size to the width of a two star rating
4. The total width can become less than the width of the main panel (see screenshot below). In this case, columns should be wider than needed to display their contents.
6. The column widths don't take into account tracks that are off screen
7. It only works when "Keep Columns Sized to Panel" is unchecked
8. Sometimes I end up with unskinned scrollbars
9. The same key combination can be used to size columns in the Track Browser if they have input focus, which doesn't really work because there's no way to resize it again.
Tried the same keys in Album and Tracks view and got this:
Bee excellent to each other...