b1eb9e768e43105c374302cf62800fbfe8d65a5e
hiram
  Thu Mar 9 11:16:30 2017 -0800
empty string is the same as All refs #18656

diff --git src/hg/hgTracks/chainTrack.c src/hg/hgTracks/chainTrack.c
index 5e79f7f..2150a8e 100644
--- src/hg/hgTracks/chainTrack.c
+++ src/hg/hgTracks/chainTrack.c
@@ -408,31 +408,31 @@
 int rowOffset;
 char **row;
 struct sqlConnection *conn = hAllocConn(database);
 struct sqlResult *sr = NULL;
 struct linkedFeatures *list = NULL, *lf;
 int qs;
 char *optionChrStr;
 char extraWhere[128] ;
 struct cartOptions *chainCart;
 
 chainCart = (struct cartOptions *) tg->extraUiData;
 
 optionChrStr = skipLeadingSpaces(cartUsualStringClosestToHome(cart, tg->tdb,
     FALSE, "chromFilter", "All"));
 
-if (differentWord("All",optionChrStr))
+if (strlen(optionChrStr) > 0 && differentWord("All",optionChrStr))
     {
     safef(extraWhere, sizeof(extraWhere),
             "qName = \"%s\" and score > %d",optionChrStr,
             chainCart->scoreFilter);
     sr = hRangeQuery(conn, table, chromName, winStart, winEnd,
             extraWhere, &rowOffset);
     }
 else
     {
     if (chainCart->scoreFilter > 0)
         {
         safef(extraWhere, sizeof(extraWhere),
                 "score > \"%d\"",chainCart->scoreFilter);
         sr = hRangeQuery(conn, table, chromName, winStart, winEnd,
                 extraWhere, &rowOffset);