I used Helvetica font and it worked fine to me.
Thank you for the test. Helvetica gives me almost the same result as Arial on my system (See my initial email message with sample plots attached): The numeric values 20– touch the colorbar.
Might be a Mac problem or might be only a certain font type.
So, it's more likely a Mac problem.
Cheers,
Ryo
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Off topic: As expected the hyphen character in Helvetica is somewhat stubbier than in Arial. But for this "minus sign", I would prefer Helvetica. . . .