--- loncom/xml/lontexconvert.pm	2007/06/19 20:10:55	1.83
+++ loncom/xml/lontexconvert.pm	2008/07/18 13:09:33	1.88
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # TeX Conversion Module
 #
-# $Id: lontexconvert.pm,v 1.83 2007/06/19 20:10:55 albertel Exp $
+# $Id: lontexconvert.pm,v 1.88 2008/07/18 13:09:33 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -108,6 +108,14 @@ sub convert_real {
     $xmlstring=~s/^\s*\<br clear\=\"all\"/\<br/s;
     $xmlstring=~s/^\s*//;
     $xmlstring=~s/\s*$//;
+    #
+    # \rightleftharpoons is not converted by tth but maps
+    # reasonably well to &#8660;.  If we get many more of these,
+    # we're going to need to have a translation sub.
+    #
+    my $lrharpoon = pack("U", 0x21cc);
+    $xmlstring=~s/\\rightleftharpoons/$lrharpoon/g;
+
     &Apache::lonxml::end_alarm();
     return ($xmlstring,$errorstring);
 }
@@ -203,11 +211,17 @@ sub jsMath_converted {
 	return "\n".
 	    '<script type="text/javascript">jsMath.Process()</script>'."\n";
     }
+    sub jsMath_state {
+	my ($level) = @_;
+	return $jsMath_sent_header[$level];
+    }
 }
 
 sub tex_engine {
     if (exists($env{'form.texengine'})) {
-	return $env{'form.texengine'};
+	if ($env{'form.texengine'} ne '') {
+            return $env{'form.texengine'};
+        }
     }    
     if ($env{'request.course.id'}
 	&& exists($env{'course.'.$env{'request.course.id'}.'.texengine'})) {
@@ -220,9 +234,11 @@ sub tex_engine {
 }
 
 sub init_math_support {
+    my ($inherit_jsmath) = @_;
     &init_tth();
     &Apache::lontexconvert::jsMath_push();
-    if (lc(&tex_engine()) eq 'jsmath') {
+    if (lc(&tex_engine()) eq 'jsmath' ||
+	($inherit_jsmath && &jsMath_state(-2))) {
 	return &Apache::lontexconvert::jsMath_header();
     }
     return;