open the correct view based on which item you are creating and on the content of the stylesheet file

src/Umbraco.Web.UI.Client/src/views/stylesheets/create.html

@@ -12,7 +12,7 @@
             </li>
             <li class="umb-action">
                 <a href="" ng-click="vm.createRichtextStyle()" class="umb-action-link">
-                    <i class="large icon icon-folder"></i>
+                    <i class="large icon icon-script"></i>
                     <span class="menu-label"><localize key="create_newRteStyleSheetFile">New richtext style sheet file</localize></span>
                 </a>
             </li>

src/Umbraco.Web.UI.Client/src/views/stylesheets/edit.controller.js

@@ -12,24 +12,6 @@
         vm.page.menu.currentNode = null;
         vm.page.saveButtonState = "init";
 
-        localizationService.localizeMany(["stylesheet_tabCode", "stylesheet_tabRules"]).then(function (data) {
-            vm.page.navigation = [
-                {
-                    "name": data[0],
-                    "alias": "code",
-                    "icon": "icon-brackets",
-                    "view": "views/stylesheets/views/code/code.html",
-                    "active": true
-                },
-                {
-                    "name": data[1],
-                    "alias": "rules",
-                    "icon": "icon-font",
-                    "view": "views/stylesheets/views/rules/rules.html"
-                }
-            ];
-        });
-
          //Used to toggle the keyboard shortcut modal
         //From a custom keybinding in ace editor - that conflicts with our own to show the dialog
         vm.showKeyboardShortcut = false;
@@ -45,7 +27,10 @@
             vm.page.keyboardShortcutsOverview.push(shortcuts);
         });
 
-        vm.stylesheet = {};
+        vm.stylesheet = {
+            content: "",
+            rules: []
+        };
 
         // bind functions to view model
         vm.save = interpolateAndSave;
@@ -139,16 +124,47 @@
 
             if ($routeParams.create) {
                 codefileResource.getScaffold("stylesheets", $routeParams.id).then(function (stylesheet) {
+                    const mode = $routeParams.rtestyle ? "RTE" : null;
                     ready(stylesheet, false);
+                    generateNavigation(mode);
                 });
             } else {
                 codefileResource.getByPath('stylesheets', $routeParams.id).then(function (stylesheet) {
                     ready(stylesheet, true);
+                    extractRules().then(rules => {
+                        vm.stylesheet.rules = rules;
+                        const mode = rules && rules.length > 0 ? "RTE" : null;
+                        generateNavigation(mode);
+                    });
                 });
             }
 
         }
 
+        function generateNavigation(mode) {
+            localizationService.localizeMany(["stylesheet_tabRules", "stylesheet_tabCode"]).then(function (data) {
+                vm.page.navigation = [
+                    {
+                        "name": data[0],
+                        "alias": "rules",
+                        "icon": "icon-font",
+                        "view": "views/stylesheets/views/rules/rules.html"
+                    },
+                    {
+                        "name": data[1],
+                        "alias": "code",
+                        "icon": "icon-brackets",
+                        "view": "views/stylesheets/views/code/code.html"
+                    }
+                ];
+                if(mode === "RTE") {
+                    vm.page.navigation[0].active = true;
+                } else {
+                    vm.page.navigation[1].active = true;
+                }
+            });
+        }
+
         function ready(stylesheet, syncTree) {
 
             vm.page.loading = false;
@@ -244,7 +260,7 @@
         }
 
         function extractRules() {
-            return codefileResource.extractStylesheetRules(vm.stylesheet.content, null);
+            return codefileResource.extractStylesheetRules(vm.stylesheet.content);
         }
         
         $scope.selectApp = function (app) {

src/Umbraco.Web.UI.Client/src/views/stylesheets/views/rules/rules.controller.js

@@ -16,6 +16,9 @@ angular.module("umbraco").controller("Umbraco.Editors.StyleSheets.RulesControlle
             evt.preventDefault();
 
             openOverlay({}, $scope.labels.addRule, (newRule) => {
+                if(!$scope.model.stylesheet.rules) {
+                    $scope.model.stylesheet.rules = [];
+                } 
                 $scope.model.stylesheet.rules.push(newRule);
                 setDirty();
             });