--- loncom/homework/structuretags.pm	2002/01/24 04:18:54	1.78
+++ loncom/homework/structuretags.pm	2002/01/30 17:37:21	1.79
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA 
 # definition of tags that give a structure to a document
 #
-# $Id: structuretags.pm,v 1.78 2002/01/24 04:18:54 harris41 Exp $
+# $Id: structuretags.pm,v 1.79 2002/01/30 17:37:21 albertel Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -67,24 +67,39 @@ sub end_tex {
 
 sub page_start {
   my ($target,$token,$tagstack,$parstack,$parser,$safeeval)=@_;
-  my $result=&Apache::londefdef::start_html($target,$token,$tagstack,$parstack,$parser,$safeeval);
-  my $head_tag_start='<head>'.&Apache::lonxml::registerurl();
-  my $body_tag_start='<body onLoad="'.&Apache::lonxml::loadevents().'" '.
-	  'onUnload="'.&Apache::lonxml::unloadevents().'" ';
-  my $background=&Apache::lonxml::get_param('background',$parstack,$safeeval);
-  if ($background) {
-    $Apache::lonxml::extlinks[$#Apache::lonxml::extlinks+1]=
-                                        $background;
-    $body_tag_start.='background="'.$background.'" ';
-  } else {
-    my $bgcolor=&Apache::lonxml::get_param('bgcolor',$parstack,$safeeval);
-    if ($bgcolor) {
-      $body_tag_start.='bgcolor="'.$bgcolor.'" ';
+  my %found;
+  foreach my $taginside ($tagstack) {
+    foreach my $taglookedfor ('html','body','form') {
+      if ($taginside =~ /^$taglookedfor$/i) { $found{$taglookedfor} = 1; }
+    }
+  }
+
+  my $result;
+  my $head_tag_start;
+  if (!defined($found{'html'})) {
+    $result=&Apache::londefdef::start_html($target,$token,$tagstack,$parstack,
+					   $parser,$safeeval);
+    $head_tag_start='<head>'.&Apache::lonxml::registerurl();
+  }
+  my $body_tag_start;
+  if (!defined($found{'body'})) {
+    my $body_tag_start='<body onLoad="'.&Apache::lonxml::loadevents().'" '.
+      'onUnload="'.&Apache::lonxml::unloadevents().'" ';
+    my $background=&Apache::lonxml::get_param('background',$parstack,$safeeval);
+    if ($background) {
+      $Apache::lonxml::extlinks[$#Apache::lonxml::extlinks+1]=
+	$background;
+      $body_tag_start.='background="'.$background.'" ';
     } else {
-      $body_tag_start.='bgcolor="#ffffff"';
+      my $bgcolor=&Apache::lonxml::get_param('bgcolor',$parstack,$safeeval);
+      if ($bgcolor) {
+	$body_tag_start.='bgcolor="'.$bgcolor.'" ';
+      } else {
+	$body_tag_start.='bgcolor="#ffffff"';
+      }
     }
+    $body_tag_start.='>';
   }
-  $body_tag_start.='>';
   return ($result,$head_tag_start,$body_tag_start);
 }
 
@@ -147,6 +162,11 @@ ENDCHECKOUT
 sub start_problem {
   my ($target,$token,$tagstack,$parstack,$parser,$safeeval)=@_;
 
+  if ( $Apache::inputtags::part ne '' ) {
+    &Apache::lonxml::error('Only one problem allowed in a .problem file');
+    my $bodytext=&Apache::lonxml::get_all_text("/problem",$$parser[-1]);
+    return '';
+  }
 #intialize globals
   $Apache::inputtags::part='0';
   @Apache::inputtags::responselist = ();
