Tab insertion via document.execCommand

app/assets/javascripts/app/frontend/controllers/editor.js

@@ -516,6 +516,10 @@ angular.module('app.frontend')
       var handleTab = function (event) {
         if (!event.shiftKey && event.which == 9) {
           event.preventDefault();
+
+          // Using document.execCommand gives us undo support
+          if(!document.execCommand("insertText", false, "\t")) {
+            // document.execCommand works great on Chrome/Safari but not Firefox
             var start = this.selectionStart;
             var end = this.selectionEnd;
             var spaces = "    ";
@@ -527,6 +531,7 @@ angular.module('app.frontend')
             // Place cursor 4 spaces away from where
             // the tab key was pressed
             this.selectionStart = this.selectionEnd = start + 4;
+          }
 
           parent.note.text = this.value;
           parent.changesMade();