I've just found what appears to be a bug with nested transforms where:
	* inner has a rotation but no scale
	* outer has only an offset

Here's a Workspace session that demonstrates this:

m _ Morph new.
m openInWorld.
m position: 100 at 100.
t _ m transformFrom: m world." an IdentityTransform"
(t localPointToGlobal: m center)" 125 at 120"
f _ m addFlexShell.
t _ m transformFrom: m world." a MorphicTransform(angle = 0.0; scale =
1.0; offset = -125 at -120)"
(t localPointToGlobal: m center)" 125 at 120"
f angle: 45.0.
t _ m transformFrom: m world." a MorphicTransform(angle = 45.0; scale =
1.0; offset = -125 at -120)"
(t localPointToGlobal: m center)" 125.0 at 120.0"

"Now look at this: adding a shell hasn't moved the morph at all. But its
transform
reports that its center has shifted to negative land:"

ff _ f addFlexShell.
t _ m transformFrom: m world." a MorphicTransform(angle = 45.0; scale =
1.0; offset = 123 at 118)"
(t localPointToGlobal: m center)" -123.0 at -118.0"

"Ah, but if we change the scale to something other than 1, everything's
happy:"

ff scale: 1.000001.
t _ m transformFrom: m world." a CompositeTransform"
(t localPointToGlobal: m center)" 125.000001 at 120.000001"

ff delete