The HAPPY NEW YEAR commit

The HAPPY NEW YEAR commit

This should close sf #2850092.
Basically, before this change, for strings which includes
SECRIT_MULTILINE_CHAR the computed maximum substring width was getting
summed to the width of the last substring.
The old behaviour is kept but for the case of strings including
SECRIT_MULTILINE_CHAR, for which now the maximum width of all substrings
is taken.
I don't think this will break anything else but blame me if it does ...
(cherry picked from commit 72bbe51a8c323702db76094e27266e67cc1ba5b5)