Issue with the sidebar calendar

Sunday in Spanish is Domingo. The shortened (three-character) phrase should be Dom.. I have decided to omit the final . in the translation to save space. However, there is a issue with the calendar in the sidebar.

One solution would be to add an even shorter phrases, as Google Calendar does, to use a one-character phrases S M T W T F S. It could be a solution to this problem and would give more versatility to the software.

Yes, I can to change Sun to S in the language file, but in this case the short phrase is unusable except for the calendar.

Edit. It seems that there is no written rule on how to abbreviate the days of the week in Spanish. Some sources propose to abbreviate using two character and a dot Do.. This seems to be a good solution at the moment. In any case, the current three-character format fails with the width of some characters in the side calendar.

I have just realised that this also happens in the English language. Check what happens with Mon column.