Display warning on tab close if message contents are not empty

admin/admin_ticket.php

@@ -1949,6 +1949,7 @@ function hesk_printReplyForm()
 
                             ?></textarea>
                         <div class="help-block with-errors" id="message-help-block"></div></span>
+                        <p id="lang_ticket_message_contents_exist" style="display: none"><?php echo $hesklang['ticket_message_contents_exist']; ?></p>
                 </div>
             </div>
             <?php

internal-api/js/admin-ticket.js

@@ -41,5 +41,29 @@ $(document).ready(function() {
     $('#related-tickets-link').click(function() {
         $(this).hide();
         $('.related-ticket').show();
-    })
+    });
+
+    window.onbeforeunload = function (e) {
+        e = e || window.event;
+
+        var plaintextEditorHasContents = $('textarea[name="message"]').val() !== '';
+        var htmlEditorHasContents = false;
+
+        if (tinymce.get("message") !== undefined) {
+            plaintextEditorHasContents = false;
+            htmlEditorHasContents = tinymce.get("message").getContent() !== '';
+        }
+
+        if (plaintextEditorHasContents || htmlEditorHasContents) {
+            var $langText = $('#lang_ticket_message_contents_exist');
+
+            // For IE and Firefox prior to version 4
+            if (e) {
+                e.returnValue = $langText.text();
+            }
+
+            // For Safari
+            return $langText.text();
+        }
+    };
 });

language/en/text.php

@@ -47,6 +47,7 @@ $hesklang['EMAIL_HR']='------ Reply above this line ------';
 
 // ADDED OR MODIFIED IN Mods for HESK 3.1.0
 $hesklang['stack_trace_header'] = 'Stack Trace';
+$hesklang['ticket_message_contents_exist'] = 'The ticket message is not empty. Are you sure you want to leave this page?';
 
 // ADDED OR MODIFIED IN Mods for HESK 3.0.0
 $hesklang['you_have_x_messages'] = 'You have %s new %s'; // %s: Number of new messages, "message" or "messages", depending on #