Of course!  Right after just posting those test results I encountered
a bug with debugging case statements.

| str char | str := '1234' readStream.
char := str next.
char ifNil: [ Error signal ].
char caseOf: {
    [$4] -> ['four'].
    [$3] -> ['three' asUppercase].
    [$2] -> ['two'].
    [$1] -> ['one' asUppercase].
} otherwise: [ 'No' ]

The issue is that it highlights "signal" of "Error signal".

It's also interesting, but somewhat understandable, that it doesn't
highlight the blocks with no message sends in them.

Best,
  Chris