Allow "show source" button.

main/exercise/UniqueAnswerImage.php

@@ -30,11 +30,11 @@ class UniqueAnswerImage extends UniqueAnswer
     public function createAnswersForm($form)
     {
         $objExercise = Session::read('objExercise');
-        $editorConfig = array(
-            'ToolbarSet' => 'TestFreeAnswer',
+        $editorConfig = [
+            'ToolbarSet' => 'TestProposedAnswer',
             'Width' => '100%',
             'Height' => '125'
-        );
+        ];
 
         //this line defines how many questions by default appear when creating a choice question
         // The previous default value was 2. See task #1759.