MDL-6649 Only show the HTML editor for the first essay question on a …

…page, since it is unreliable when there are lots.

lang/en_utf8/help/quiz/essay.html

@@ -6,6 +6,10 @@
    chosen by the facilitator.</p>
 
 <p>The essay question will not be assigned a grade until it has been reviewed by a teacher 
-    or facilitator by using the Manual Grading feature.  When manually grading an essay
-    question, the grader will be able to enter a custom comment in response the respondent's
-    essay and be able to assign a score for the essay.</p>
+   or facilitator by using the Manual Grading feature.  When manually grading an essay
+   question, the grader will be able to enter a custom comment in response the respondent's
+   essay and be able to assign a score for the essay.</p>
+
+<p>Normally, the student can type their answer using the rich-text editor. However,
+   if there is more than one essay question on a page, the rich-text editor is
+   only used for the first essay question.</p>

question/type/essay/questiontype.php

@@ -37,10 +37,13 @@ function save_question_options($question) {
 
     function print_question_formulation_and_controls(&$question, &$state, $cmoptions, $options) {
         global $CFG;
+        static $htmleditorused = false;
 
         $answers       = &$question->options->answers;
         $readonly      = empty($options->readonly) ? '' : 'disabled="disabled"';
-        $usehtmleditor = can_use_html_editor();
+
+        // Only use the rich text editor for the first essay question on a page.
+        $usehtmleditor = can_use_html_editor() && !$htmleditorused;
 
         $formatoptions          = new stdClass;
         $formatoptions->noclean = true;
@@ -87,6 +90,7 @@ function print_question_formulation_and_controls(&$question, &$state, $cmoptions
 
         if ($usehtmleditor) {
             use_html_editor($inputname);
+            $htmleditorused = true;
         }
     }