Box markup box not a square

[Arjan Bos]

Hi list,

I'm using 2.4.2

In my pieces I like to have the default marks (with \mark \default) to 
be in a box. As per documentation I use the following lisp code:

    \set Score.markFormatter = #(lambda (mark  context)
                                 (make-box-markup
                                  (format-mark-letters mark context)))

And this results in a box that isn't square. A picture of it (zoomed in 
quite a few times) can be found at:

http://zaaf.nl/unsquareBox.pdf
(It's a pdf-file of a screen capture, don't ask ;-)

Please notice that the right hand line of the square has moved a bit to 
the left.

Is this a bug? Or can I make the box square.

By the way:
The boxes look square on paper and in the end that's what counts. So it 
might just be a display issue here.

Kind regards,
Arjan Bos

---
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