--- loncom/xml/londefdef.pm	2016/01/06 16:44:37	1.457
+++ loncom/xml/londefdef.pm	2016/07/01 19:59:25	1.459
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # Tags Default Definition Module 
 #
-# $Id: londefdef.pm,v 1.457 2016/01/06 16:44:37 damieng Exp $
+# $Id: londefdef.pm,v 1.459 2016/07/01 19:59:25 raeburn Exp $
 # 
 #
 # Copyright Michigan State University Board of Trustees
@@ -92,6 +92,14 @@ sub start_m {
     my $inside = &Apache::lonxml::get_all_text_unbalanced("/m",$parser);
     if ($target eq 'web' || $target eq 'analyze') {
 	&Apache::lonxml::debug("M is starting with:$inside:");
+        if (!($inside =~ /^\s*\$.*\$\s*$/ || $inside =~ /^\s*\\[([].*\\[)\]]\s*$/)) {
+            # Non-math LaTeX will not be rendered correctly with MathJax
+            # and it should be avoided anyway.
+            # On top of that, MathJax will render math without $, but
+            # it will fail with tth. This is worth a warning.
+            # (even though some people might just use latex for printing)
+            &Apache::lonxml::warning(&mt("Missing \$ in <m>."));
+        }
 	my $eval=&Apache::lonxml::get_param('eval',$parstack,$safeeval);
 	if ($eval eq 'on') {
 	    $inside=&Apache::run::evaluate($inside,$safeeval,$$parstack[-1]);
@@ -2864,8 +2872,8 @@ sub start_img {
         my $only = join(',',&Apache::loncommon::filecategorytypes('Pictures'));
 	$currentstring .=&Apache::edit::tag_start($target,$token);
 	$currentstring .=&Apache::edit::text_arg('Image Url:','src',$token,70).
-	    &Apache::edit::browse('src',undef,'alt',$only).' '.
-	    &Apache::edit::search('src',undef,'alt').'<br />';
+                         &Apache::edit::browse_or_search('src',undef,'alt',$only,undef,1).
+                         '<br />';
 	$currentstring .=&Apache::edit::text_arg('Description:','alt',$token,70).'<br />';
 	$currentstring .=&Apache::edit::text_arg('width (pixel):','width',$token,5);
 	$currentstring .=&Apache::edit::text_arg('height (pixel):','height',$token,5).'<br />';
@@ -2887,17 +2895,19 @@ sub start_img {
 	my $src=    &Apache::lonxml::get_param('src',$parstack,$safeeval);
 	my $width=  &Apache::lonxml::get_param('width',$parstack,$safeeval);
 	my $height= &Apache::lonxml::get_param('height',$parstack,$safeeval);
-
+        my $element = &Apache::edit::get_element('src'); 
+        my $text;
         if ($token->[2]{'src'}=~/\$/) {
-           $currentstring.=&mt('Variable image source');
+           $text = &mt('Variable image source');
         } elsif ($token->[2]{'src'}=~/\S/) {
 	   $currentstring .= '<img src="'.$src.'" alt="'.$alt.'" ';
 	   if ($width) { $currentstring.=' width="'.$width.'" '; }
 	   if ($height) { $currentstring.=' height="'.$height.'" '; }
-	   $currentstring .= ' />';
+	   $currentstring .= ' id="previewimg_'.$element.'" />';
         } else {
-           $currentstring.=&mt("No image source specified");
+           $text = &mt("No image source specified");
         }
+        $currentstring .= ' <span id="showimg_'.$element.'">'.$text.'</span>';
     } elsif ($target eq 'modified') {
 	my ($osrc,$owidth,$oheight)=
 	    ($token->[2]{'src'},$token->[2]{'width'},$token->[2]{'height'});