It looks like this had nothing to do with the size of the class text.
It is the same issue as reported by Roger Osmond: https://groups.google.com/forum/?utm_medium=email&utm_source=footer#!msg/eiffel-users/6cZe_8JVbEg/r5QEXsc2CgAJ
In our case we are using "[  ... ]", not "{ ... }".
Adding a space after the closing quote works as a workaround.

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Eric Bezault