--- loncom/homework/optionresponse.pm	2006/03/09 01:04:43	1.133
+++ loncom/homework/optionresponse.pm	2006/03/15 00:08:53	1.134
@@ -1,7 +1,7 @@
 # LearningOnline Network with CAPA
 # option list style responses
 #
-# $Id: optionresponse.pm,v 1.133 2006/03/09 01:04:43 albertel Exp $
+# $Id: optionresponse.pm,v 1.134 2006/03/15 00:08:53 foxr Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -481,6 +481,65 @@ sub displayfoils {
 }
 
 
+#  Correct a single option list element.
+#  - For embedded <display></display> tags,
+#    we pass literally the stuff between them.
+#  - For everything else, we run through latex_special_symbols
+#    so that any symbols that have meaning to LaTeX will be
+#    correctly escaped.
+#
+sub correct_option {
+    my $option = shift;
+
+
+    # There's probably a beter way with perl if I was
+    # more of a regexp wiz..(RF).
+
+    my $strlen = length($option);
+    my $here   = 0;		# Where to start searching for <display></display>
+    my $result ="";		# The return string is built here.
+    
+    while ($here < $strlen) {
+	# look for an opening <display> tag:
+
+	my $openloc = index($option, "<display>", $here);
+	if ($openloc == -1) {
+	    # No more... operate with latex_special_symbols on
+	    # the rest of the string.
+
+	    $result .= &Apache::lonxml::latex_special_symbols(substr($option, $here));
+	    return $result;
+	} else {
+	    # Need to pass the string up to the <display> tag 
+	    # through l_s_s ...
+	    $result .= &Apache::lonxml::latex_special_symbols(substr($option, $here, $openloc-$here));
+	}
+	# look for the closing </display> tag...
+	# We're a bit stupid..or tolerant...
+	# in that if the user forgets the </display> tag
+	# we infer they intended one at the end of the option.
+	$openloc += 9;		# 9 chars in <display>
+
+	my $closeloc = index($option, "</display>", $openloc); # 9 chars in <display>
+	if ($closeloc == -1) {
+	    $closeloc = $strlen + 9;                             # 10chars in </display> faked off end. 
+	}
+	#  Pass from openloc through closeloc without any interpretation:
+
+	&Apache::lonnet::logthis("Segment inside display: $openloc through $closeloc");
+	$result .= substr($option, $openloc, $closeloc - $openloc);
+	$here    = $closeloc + 10;                               # Next search is after the </display> 
+    }
+
+    return $result;
+
+    # return &Apache::lonxml::latex_special_symbols($option);
+}
+
+#  Correct the option list elements so that if there
+#  are special symbosl that have meaning to LaTeX
+#  they get fixed up to display correctly.
+
 sub optionlist_correction {
     my ($TeXlayout,@options) = @_;
     my $texoptionlist='\\item [] Choices: ';
@@ -488,7 +547,7 @@ sub optionlist_correction {
     if (scalar(@options) > 0) {
 	foreach my $option (@options) {
 	    $texoptionlist.='{\bf '.
-		&Apache::lonxml::latex_special_symbols($option).
+		&correct_option($option).
 		'}';
 	    if ($TeXlayout eq 'vertical') {
 		$texoptionlist.=' \vskip 0 mm ',