In my porting of my old Morphs to the new Alignment stuff, I noticed that my 
PluggableButtonMorphs started misbehaving.  Here's a quick example:

(PluggableButtonMorph new label: 'blah') openInWorld

If you execute the above snipped pre-alignment-rewrite, you'll get a nice 
button sized properly around the label. If you execute it post-rewrite, the 
button is a small off-side rectangle and the label sticks out of the end.

I compared the code pre- and post- rewrite and I don't see anything 
obvious...the AlignmentMorph in PluggableButtonMorph>>label: looks to my eyes 
to be okay (of course I'm still green with the new alignment code :).

Is this a new bug, or new functionality? :)

Incidentally I did notice a very small change to the AlignmentMorph behaviour 
with respect to calculating it's extent.  If you add some morphs to an 
AlignmentMorph, the extent of the AlignmentMorph doesn't get updated to the 
'new' extent until you open it in the world.  In the pre-rewrite days, adding 
the unmapped AlignmentMorph to another Morph would force the recalculation of 
it's extent as though it had been opened in the World.  Post rewrite, it does 
not do this anymore (I used to use this little gimmick :).  Could this be 
related?

(Oh and this is in 2.9a, using an image with the most-up-to-date changes).