Comment 10 for bug 156643

This may be due to what's describe in the hyperref doc: http://www.tug.org/applications/hyperref/ftp/README

  * Be aware that not all PDF viewers support this feature, not
    even Acrobat Reader itself:

    Some support:
    * AR7/Linux: "underline" and "dashed", but the border width
      must be given.
    * xpdf 3.00: "underline" and "dashed"

    Unsupported:
    * AR5/Linux
    * ghostscript 8.50

So it may be that these boxes were there (in the doc) before, but weren't supported in poppler or acrobat reader, and now they are (?)