### Eclipse Workspace Patch 1.0
#P moodle20
Index: mod/lesson/mod_form.php
===================================================================
RCS file: /cvsroot/moodle/moodle/mod/lesson/mod_form.php,v
retrieving revision 1.40
diff -u -r1.40 mod_form.php
--- mod/lesson/mod_form.php	2 Sep 2010 18:29:40 -0000	1.40
+++ mod/lesson/mod_form.php	4 Dec 2010 17:21:00 -0000
@@ -258,13 +258,19 @@
 
 //-------------------------------------------------------------------------------
         $mform->addElement('header', 'mediafileheader', get_string('mediafile', 'lesson'));
-
+        // devjr
+        $mform->addElement('checkbox', 'deletepicture', get_string('delete'));
+        $mform->setDefault('deletepicture', 0);
+		$mform->disabledIf($elementName='deletepicture', $dependentOn='mediafile', $condition = 'eq', $value='');
+        // end devjr
         $filepickeroptions = array();
         $filepickeroptions['filetypes'] = '*';
         $filepickeroptions['maxbytes'] = $this->course->maxbytes;
         $mform->addElement('filepicker', 'mediafilepicker', get_string('mediafile', 'lesson'), null, $filepickeroptions);
         $mform->addHelpButton('mediafilepicker', 'mediafile', 'lesson');
 
+        
+        
 //-------------------------------------------------------------------------------
         $mform->addElement('header', 'dependencyon', get_string('dependencyon', 'lesson'));
 
@@ -306,7 +312,7 @@
      * @return void
      **/
     function data_preprocessing(&$default_values) {
-        global $DB;
+    	global $DB;
         global $module;
         if (isset($default_values['conditions'])) {
             $conditions = unserialize($default_values['conditions']);
@@ -318,10 +324,9 @@
         if (isset($default_values['password']) and ($module->version<2008112600)) {
             unset($default_values['password']);
         }
-
-        if ($this->current->instance) {
+        if ($this->current->instance && $this->current->mediafile) {
             // editing existing instance - copy existing files into draft area
-            $draftitemid = file_get_submitted_draft_itemid('mediafilepicker');
+        	$draftitemid = file_get_submitted_draft_itemid('mediafilepicker');
             file_prepare_draft_area($draftitemid, $this->context->id, 'mod_lesson', 'mediafile', 0, array('subdirs'=>0, 'maxbytes' => $this->course->maxbytes, 'maxfiles' => 1));
             $default_values['mediafilepicker'] = $draftitemid;
         }
Index: mod/lesson/lib.php
===================================================================
RCS file: /cvsroot/moodle/moodle/mod/lesson/lib.php,v
retrieving revision 1.107
diff -u -r1.107 lib.php
--- mod/lesson/lib.php	21 Sep 2010 08:37:39 -0000	1.107
+++ mod/lesson/lib.php	4 Dec 2010 17:21:00 -0000
@@ -87,7 +87,7 @@
     $DB->update_record("lesson", $data);
 
     $context = get_context_instance(CONTEXT_MODULE, $cmid);
-    if ($filename = $mform->get_new_filename('mediafilepicker')) {
+    if (!isset($data->deletepicture) && $filename = $mform->get_new_filename('mediafilepicker')) {
         if ($file = $mform->save_stored_file('mediafilepicker', $context->id, 'mod_lesson', 'mediafile', 0, '/', $filename, true)) {
             $DB->set_field('lesson', 'mediafile', '/'.$file->get_filename(), array('id'=>$data->id));
         } else {
@@ -96,7 +96,6 @@
     } else {
         $DB->set_field('lesson', 'mediafile', '', array('id'=>$data->id));
     }
-
     lesson_process_post_save($data);
 
     // update grade item definition