c315c738489bdd9029742f0a58dae14cc4b98e09
max
  Thu Mar 2 11:41:07 2017 -0800
adding some doc about new keyboard shortcut, refs #18936

diff --git src/hg/js/hgTracks.js src/hg/js/hgTracks.js
index 5bf56bc..248fa8c 100644
--- src/hg/js/hgTracks.js
+++ src/hg/js/hgTracks.js
@@ -1049,31 +1049,32 @@
                 cartSettings.nonVirtHighlight = hgTracks.highlight;
         }
         // TODO if not virt, do we need to erase cart nonVirtHighlight ?
         cart.setVarsObj(cartSettings);
         imageV2.highlightRegion();
     },
 
     selectionEndDialog: function (newPosition)
     // Let user choose between zoom-in and highlighting.
     {   
         var dragSelectDialog = $("#dragSelectDialog")[0];
         if (!dragSelectDialog) {
             $("body").append("<div id='dragSelectDialog'><span id='dragSelectPosition'></span>" + 
                              "<p><input type='checkbox' id='disableDragHighlight'>" + 
                              "Don't show this dialog again and always zoom.<BR>" + 
-                             "(Re-enable highlight via the 'configure' menu at any time.)</p>");
+                             "(Re-enable highlight via the 'configure' menu at any time.)</p>"+ 
+                             "Using the keyboard, you can highlight the current position with 'm then a' and clear all highlights with 'm then c'.<p>");
             dragSelectDialog = $("#dragSelectDialog")[0];
         }
         if (hgTracks.windows) {
             var i,len;
             var newerPosition = newPosition;
             if (hgTracks.virtualSingleChrom && (newPosition.search("virt:")===0)) {
                 newerPosition = genomePos.disguisePosition(newPosition);
             }
             var str = newerPosition + "<br>\n";
             var str2 = "<br>\n";
             str2 += "<ul style='list-style-type:none; max-height:200px; padding:0; width:80%; overflow:hidden; overflow-y:scroll;'>\n";
             var pos = parsePosition(newPosition);
             var start = pos.start - 1;
             var end = pos.end;
             var selectedRegions = 0;