anchor.diff:      This highlights C++ style comments in cyan, with an eventual 'TODO:'
       in yellow on red background:
   
  --------------------------------------------------------------------
  -add-highlighter window regex //\h*(TODO:)[^\n]* 0:cyan 1:yellow,red
  --------------------------------------------------------------------
  +--------------------------------------------------------------------
  +add-highlighter window/ regex //\h*(TODO:)[^\n]* 0:cyan 1:yellow,red
  +--------------------------------------------------------------------
   
   *dynregex* <expression> <capture_id>:<face> ...::
       similar to regex, but expand (like a command parameter would) the
       given expression before building a regex from the result.
       This highlights all the current search matches in italic:
   
  -----------------------------------------------
  -add-highlighter window dynregex '%reg{/}' 0:+i
  -----------------------------------------------
  +-----------------------------------------------
  +add-highlighter window/ dynregex '%reg{/}' 0:+i
  +-----------------------------------------------
   
   == Specs highlighters
   
  
positive.code: shell_expand %sh\{ \} \{
  ------------------------
  
  Regions are used in the region highlighters which can take any number
  of regions.
  
  The following command:
  
  ------------------------------------------------------
  add-highlighter <path> regions <name> \
      <region_name1> <opening1> <closing1> <recurse1> \
      <region_name2> <opening2> <closing2> <recurse2>...
  ------------------------------------------------------
  
  defines multiple regions in which other highlighters can be added as follows:
  
  -----------------------------------------------
  add-highlighter <path>/<name>/<region_name> ...
  -----------------------------------------------
  
  Regions are matched using the left-most rule: the left-most region opening
  starts a new region. When a region closes, the closest next opening start
  another region.
  
  That matches the rule governing most programming language parsing.
  
  Regions also supports a *-default <default_region>* switch to define the
  default region, when no other region matches the current buffer range.
  
  If the *-match-capture* switch is passed, then region closing and recurse
  matches are considered valid for a given region opening match only if they
  matched the same content for the capture 1.
  
  Most programming languages can then be properly highlighted using a region
  highlighter as root:
  
  -----------------------------------------------------------------
  add-highlighter <path> regions -default code <lang> \
      string <str_opening> <str_closing> <str_recurse> \
      comment <comment_opening> <comment_closing> <comment_recurse>
  
  add-highlighter <path>/<lang>/code ...
  add-highlighter <path>/<lang>/string ...
  add-highlighter <path>/<lang>/comment ...
  -----------------------------------------------------------------
  
  == Shared Highlighters
  
negative.code: 
  Highlighters can be put in the shared scope in order to make them reusable.
  
  ---------------------------------
  add-highlighter shared/<name> ...
  ---------------------------------
  
  The common case would be to create a named shared group, or regions and then
  fill it with highlighters:
  
  ---------------------------------------
  add-highlighter shared/ group <name>
  