23857d666cc77fa7c5510f2d9b85824207e28cc0
max
  Fri Nov 19 06:05:16 2021 -0800
doc'ing incognito mode, refs #28520

diff --git src/hg/htdocs/goldenPath/help/customTrackText.html src/hg/htdocs/goldenPath/help/customTrackText.html
index 3d9ddc6..066439f 100755
--- src/hg/htdocs/goldenPath/help/customTrackText.html
+++ src/hg/htdocs/goldenPath/help/customTrackText.html
@@ -733,33 +733,61 @@
   <a href="../../cgi-bin/hgTracks?db=hg19&position=chr9%3A136130563-136150630&hideTracks=1" 
   target="_blank">example link</a> to show no tracks at all</li>
   <li>
   <code>hideTracks=1&amp;&lt;trackName&gt;=full|dense|pack|hide</code> - hide all tracks and show 
   other tracks - 
   <a href="../../cgi-bin/hgTracks?db=hg19&position=chr9%3A136130563-136150630&hideTracks=1&cytoBand=pack" 
   target="_blank">example link</a> to show only the Chromosome Bands track and nothing else</li>
   <li>
   <code>highlight=&lt;db&gt;.&lt;chrom&gt;:&lt;chromStart&gt;-&lt;chromEnd&gt;#&lt;color&gt;|...</code> - 
   highlight one or more regions in a given color on the image. Note that the arguments have to be 
   URL-encoded for Internet browsers, so &quot;:&quot; becomes &quot;%3A&quot;, &quot;#&quot;
   becomes &quot;%23&quot; and &quot;|&quot; becomes &quot;%7&quot;C. - 
   <a href="../../cgi-bin/hgTracks?db=hg19&position=chr9%3A136136597-136139844&highlight=hg19.chr9%3A136138630-136139650%23AA0000%7Chg19.chr9%3A136136630-136137650%230000FF" 
   target="_blank">example link</a> to highlight two parts of the ABO locus in red and blue.</li>
   <li>
-  <code>ignoreCookie=1</code> - uses default user settings like track selections, custom
-  tracks, and track hubs - <a href="../../cgi-bin/hgTracks?db=hg19&ignoreCookie=1" 
-  target="_blank">example link</a> to show the default tracks and positions for hg19</li>
+  <code>ignoreCookie=1</code> - do not load the user's existing settings saved
+  in the internet browser's UCSC Genome Browser cookie.  This means that the link will show the Genome Browser default 
+  settings like track selections, custom tracks, and track hubs. Any changes
+  you make in this new session will however affect the user's settings.  E.g.
+  if you add a track in this new window, and come back to the genome browser
+  later, this track will appear there. This setting is useful if a website
+  wants to link to the Genome Browser, wants to start with a "clean slate" but
+  the user will most likely come back to the Genome Browser and expect the
+  changes that they made still to be there.
+  - <a href="../../cgi-bin/hgTracks?db=hg19&ignoreCookie=1" 
+  target="_blank">example link</a> to show the default tracks and positions for hg19, in a new, clean session</li>
+  <li>
+  <code>incognito=1</code> - do not load the user's existing settings saved
+  in the internet browser's UCSC Genome Browser cookie and also never save them to the cookie. 
+  This means that that link will show the Genome Browser default 
+  settings like track selections, custom
+  tracks, and track hubs. Also: Any changes made by the user or other URL arguments will not affect the user's 
+  Genome Browser settings. E.g. if you add a track in this new window, and come
+  back to the genome browser later, this track will appear NOT in the new window. This setting
+  is useful if a website wants to link to the Genome Browser, wants to start 
+  with a "clean slate" but does not want any changes to affect other Genome
+  Browser windows that are open or that the user may open later.
+  - <a href="../../cgi-bin/hgTracks?db=hg19&incognito=1" 
+  target="_blank">example link</a> to show the default tracks and positions for hg19, in a new, clean session,
+  that is completely independent from all other Genome Browser windows that the user has open or will open later.
+  Any changes made to this window won't be saved and are lost as soon as the window is closed. (At the moment,
+  there is no visual indicator in such a Genome Browser window that changes are not saved, but we could add one 
+  in the future, please contact us if you think this could be useful for you.) This variable is probably 
+  useful for most websites who use our tool hgRenderTracks to show only the
+  Browser's main image from a Javascript-driven website.
+  </li>
   <li>
   <code>oligoMatch=pack&amp;hgt.oligoMatch=&lt;dnaSeq&gt;</code> - switch on the Short Match track and 
   highlight a matching sequence - 
   <a href="../../cgi-bin/hgTracks?db=hg19&position=chr9%3A136130563-136150630&oligoMatch=pack&hgt.oligoMatch=TATAWAR" 
   target="_blank">example link</a> to highlight the TATAWAR motif in the ABO locus</li>
   <li>
   <code>pix=&lt;number&gt;</code> - set the width of the image in pixels - 
   <a href="../../cgi-bin/hgTracks?db=hg19&position=chr9%3A136130563-136150630&pix=300" 
   target="_blank">example link</a> to create a 300-pixel wide image</li>
   <li>
   <code>textSize=&lt;number&gt;</code> - set the size of text font - 
   <a href="../../cgi-bin/hgTracks?db=hg19&position=chr9%3A136130563-136150630&textSize=12" 
   target="_blank">example link</a> to increase the text font size to 12 pixels</li>
   <li>
   <code>&lt;trackName&gt;=full|dense|pack|hide</code> - show the default tracks adding a track and