Note: bugs relating to GraphViz::Data::Structure are divided into 
GraphViz::Data::Structure bugs (which I can and will fix as they
are found) and dot bugs (which I currently am not planning to fix;
dot is a large and peculiar program, with little to no internal 
documentation. My C programming expertise, what there is of it,
is committed to Perl.)
--------------------------------------------------------------------
Currently-known dot bugs (you'll have to work around these, or
endure them):
 - hashes and arrays with more than 2 elements often have a 
   "drop-shadow" extra 1-pixel-wide cell on the right-hand side.
   This is a dot bug. The "shadow" is annoying, but the graph is 
   otherwise OK.

 - self-edges sometimes generate valid dot files which dot cannot 
   process, resulting in an empty output file. This is a dot bug.
   Since most Perl data structures do not point directly to themselves,
   this isn't a big prblem.

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GraphViz::Data::Structure bugs (FIXED):

version 0.10, seventh public release
 - added code to patch the problem in GraphViz that was causing all of
   out complex record types to fail miserably

version 0.09, sixth public release
 - found and fixed a number of bugs while testing obscure features
 - many new tests
 - array-context calls now return proper results

version 0.08, fifth public release
 - fixed long-standing bug that caused all scalar refs to be interpreted
   wrongly on 5.8.0 and up

version 0.07, fourth public release
- found bug in sharing scalar data between new() and add() calls
- prettified array elements pointing to scalars (linkthru as per
  hash elements)

version 0.06, third public release
- minor changes to tests and documentation

version 0.05, second public release
 - 02types.t used localtime to generate a static test string. Changed
   to a really static string.

Version 0.04, first public release

 - "empty" cells have to be filled with a non-blank character, or
   dot draws them as zero-width cells (dot bug)
 - references to array and hash elements are not detected; they look
   like plain of scalar references