Compare draft message-ID when restoring local message contents

program/js/app.js

@@ -3131,13 +3131,20 @@ function rcube_webmail()
 
       for (var key, i = 0; i < index.length; i++) {
         key = index[i], formdata = this.local_storage_get_item('compose.' + key, null, true);
+        if (!formdata) {
+          continue;
+        }
         // restore saved copy of current compose_id
-        if (formdata && formdata.changed && key == this.env.compose_id) {
+        if (formdata.changed && key == this.env.compose_id) {
           this.restore_compose_form(key, html_mode);
           break;
         }
+        // skip records from 'other' drafts
+        if (this.env.draft_id && formdata.draft_id && formdata.draft_id != this.env.draft_id) {
+          continue;
+        }
         // show dialog asking to restore the message
-        if (formdata && formdata.changed && formdata.session != this.env.session_id) {
+        if (formdata.changed && formdata.session != this.env.session_id) {
           this.show_popup_dialog(
             this.get_label('restoresavedcomposedata')
               .replace('$date', new Date(formdata.changed).toLocaleString())
@@ -3671,6 +3678,10 @@ function rcube_webmail()
       tinyMCE.triggerSave();
     }
 
+    if (this.env.draft_id) {
+      formdata.draft_id = this.env.draft_id;
+    }
+
     $('input, select, textarea', this.gui_objects.messageform).each(function(i, elem){
       switch (elem.tagName.toLowerCase()) {
         case 'input':

program/steps/mail/compose.inc

@@ -240,6 +240,9 @@ if (!empty($msg_uid) && empty($COMPOSE['as_attachment']))
       $COMPOSE['reply_msgid'] = '<' . $in_reply_to . '>';
 
     $COMPOSE['references'] = $MESSAGE->headers->references;
+
+    // use message-ID as draft_id, same as in sendmail.inc
+    $OUTPUT->set_env('draft_id', trim($MESSAGE->headers->get('message-id'), '<>'));
   }
 }
 else {