bc2f747c9f09b2f50e0a3427e884ec34e936bf07
kate
  Wed Apr 29 16:44:24 2020 -0700
Add question mark with mouseover explanation next to hide empty subtracks checkbox. refs #23365

diff --git src/hg/lib/hui.c src/hg/lib/hui.c
index f22edc8..4afbed2 100644
--- src/hg/lib/hui.c
+++ src/hg/lib/hui.c
@@ -8650,30 +8650,33 @@
     jsIncludeFile("subCfg.js",NULL);
     }
 cgiDown(0.3);
 
 boolean hideSubtracksDefault;
 // TODO: Gray out or otherwise suppress when in multi-region mode 
 if (compositeHideEmptySubtracksSetting(tdb, &hideSubtracksDefault, NULL, NULL))
     {
     char *hideLabel = "Hide empty subtracks";
     hideLabel = trackDbSettingOrDefault(tdb, SUBTRACK_HIDE_EMPTY_LABEL, hideLabel);
     printf("<p><b>%s:</b> &nbsp;", hideLabel);
     char buf[128];
     safef(buf, sizeof buf, "%s.%s", tdb->track, SUBTRACK_HIDE_EMPTY);
     boolean doHideEmpties = compositeHideEmptySubtracks(cart, tdb, NULL, NULL);
     cgiMakeCheckBox(buf, doHideEmpties);
+    printf("<a class='toc' href='' title='Subtracks with no data in the browser window"
+                " are hidden. Changing the browser window by zooming or scrolling may result"
+                " in display of a different selection of tracks.'>?</a>");
     printf("</p>");
     }
 
 if (trackDbCountDescendantLeaves(tdb) < MANY_SUBTRACKS && !hasSubgroups)
     {
     if (primarySubtrack)
         compositeUiSubtracksMatchingPrimary(db, cart, tdb,primarySubtrack);
     else
         compositeUiSubtracks(db, cart, tdb);
     return;
     }
 if (fakeSubmit)
     cgiMakeHiddenVar(fakeSubmit, "submit");
 
 if (primarySubtrack == NULL)