
      Modification history
      --------------------
      1984/1985 Macintosh animated Christmas card
      1988/1990 Macintosh undying desk accessory, and MultiFinder version
      03DEC93 version 0 for X-windows
      04DEC93 background setting
      06DEC93 delay in main loop using select
   10DEC93 keep snow on top of windows and at bottom of display
11DEC93 snow kept sticking to the right of display (1.11)
   11DEC93 updated calcwindowtops
   12DEC93 call calcwindowtops after last exposure event only
   13DEC93 vroot added for virtual window managers
   14DEC93 separate options for snowdepth on windows and on screen
15DEC93 patch for fvwm from Mike Hollick (hollick@graphics.cis.upenn.edu)
   16DEC93 Really building up snow at bottom of screen
   16DEC93 A choice of Santa's. Thanks to Holger Veit (Holger.Veit@gmd.de)
   for Santa no. 2. Santa 1 was derived from 2 by scaling down.
   20DEC93 Aaaargh! gnu C doesn't like the initialization of the new
   Santa pixmaps. Extra braces do the trick, which is so often the case
   20DEC93 Deleted PaintSnowAtBottom. It's more of a surprise this way.
21DEC93 In case of negative x coordinates adapt width (CalcWindowTops)
   22DEC93 Rudolf's red nose. Silly. Grmbll.
   22DEC93 Bug with -nokeepsnowonwindows removed
   10JAN94 Improved handling of erasing snow at screen bottom in case of 
   window in or under the snow.
   18FEB94 X-speed really 0 inside snow layers - prevents snowflakes from 
   erasing already fallen snow a bit better
   30OCT94 More efficiency due to GC's in server and not drawing where
   the windows are.
   30OCT94 1.30 Eiichi TAZOE's code for wind included in general distribution.
   11NOV94 Bug in XRectInRegion call resolved (santa not appearing gradually
	 from behind windows)
   15NOV94 Unsigned longs changed to longs, as strtoul is troublesome on many
systems (snowDelay)
   08DEC94 Snow is really building up on windows now
   10DEC94 1.36 Handle Popups (no snow on them)
16DEC94 1.37 -offset and (-nokeepsnowonwindows and -nokeepsnowonscreen back)
   20DEC94 1.38 Let Santa be a real snowplough now
   21DEC94 1.39 VMS fix for uSsleep, thanks to Ulrich Kabatek 
   <Kaba@isr.uni-stuttgart.d400.de>
   19NOV95 1.40 Memory leak fixed in CalcWindowTops, thanks to Satoshi Asami
   <asami@cs.berkeley.edu> 
   19NOV95 1.40 Greatly increased performance when using solid backgrounds
   by using XFillRectangle instead of XClearArea. Thanks to
   Benedikt Kessler <bjk@benedikt.munich.sgi.com>
   20NOV95 1.40 Bug fixed with erasing snow at bot of screen
   1996    New macintosh version, in color http://www.euronet.nl/~rja/MacSnow/
   1998    Snow for Windows http://www.euronet.nl/~rja/WinSnow/
   18DEC2000	1.41 Fix for X-servers that do not send expose events after a
   while, due to backing store.
   14DEC2001	KDE and other root window obstructors: sub borrowed from
   xpenguins 2.2 to find the current "root" window for this system.
   Credit to Robin Hogan <R.J.Hogan@reading.ac.uk>
   dec2018 Willem: use wmctrl to find Desktop window
   invert pixmaps and display them inverted to get right
   colors on gnome desktop
   */
