+------------------------------------------------------------------------+
   |            (0) UI controls (HTML)                                      |
   +------------------------------------------------------------------------+
   |            (1) Title                                                   |
   +----+--------------------------------------------------------------+----+
   |(2) |                                                              |(4) |
   |Y-  |       (3) Main SVG drawing area                              |IPC |
   |axis|                                                              |    |
   |    |                                                              |    |
   +----+--------------------------------------------------------------+----+
   |            (5) X-axis                                                  |
   +----+--------------------------------------------------------------+----+
   |            (6) UI hint text (HTML)                                     |
   +----+--------------------------------------------------------------+----+

   List of UI active areas
   In general, click toggles buttons while shift-click cycles through more choices
   In general, shift-click-unclick to annotate/highlight; shift-click-unshift to 
     keep multiple results onscreen at once

   (0) Text and buttons
     User annotate PID names	 off/on
     All  annotate all items	 off/on

     Mark mark_x events	 	 off/both/text/numbers
     Arc  wakeup arcs		 off/on
     Lock lock-held lines	 off/on
     Slow CPU clock freq	 off/gradient
     IPC  instructions per cycle off/both/user/kernel
     Samp PC samples		 off/on
     CB   color blind colors	 off/on

     Search:    regex string match 
     !	        invert search	 off/on, like grep -v
     usec:      match only event duration in [lo..hi]
  
   (1) Title	text size	1.0/1.25/1.50/0.75 times default
  
   (2) Y-axis group triangles	collapse/expand/gray=one-fourth/gray=one-twentieth
       Y-axis labels		mouse and wheel to pan/zoom vertically
       Y-axis labels		shift-click:normal/highlight
  
   (3) anywhere 		mouse and wheel to pan/zoom horizontally	
     Red dot 			resets display
     Yellow overlay indicates slow CPU clock rate (power saving)
    
   (5) Basetime date		normal/relative to row start
  
   (6) Buttons
     1 2 3 4 5			shift-click:save, click:restore current view
     double-arrow		toggles between last two views
     [more]			this text off/on

International Morse Code (for wait events)
  A    .-    B    -...  Cpu  -.-.  Disk -.. 
  E    .     F    ..-.  G    --.   H    ....
  I    ..    J    .---  tasK -.-   Lock .-..
  Mem  --    Net  -.    O    ---   Pipe .--.
  Q    --.-  R    .-.   Sche ...   Time -   
  U    .. -  V    ...-  W    .--   X    -..-
  Y    -.--  Z    --..