* fix WindowMaker mode (I guess I broke it, but cannot test, as
  I don't use WindowMaker)

* Source = http://
   - how to configure http request header ?
   - POST ?
   - or arbirtary expect-like script for network communications ?

* real value of an indicator in tooltips

* "text" indicator (to show a string, not a number)

* optimization - when few sources have identical Source= line, read the
  file (run the script) only once and feed it to all regexes.