This fixes the DNU but doesn't centre the printed postscript text. This bug is important if printing is important for StackMorphs.
A simpler fix would be to remove the expression
(paragraph text attributesAt: offset forStyle: paragraph textStyle) do:
[:att | att emphasizeScanner: self].
from PostscriptCharacterScanner>>setTextStylesForOffset:offset.
emphasizeScanner: just calls setAlignment:. Given the proposed fix doesn't change the printed postscript, a simpler option might be better. It's possible that there is another bug or missing feature somewhere else in the printing code.
I don't know enough about StackMorph's, postscript, or Squeak's printing to take this any further.
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