chore: Add overlow scroll class for linux and windows frame

ui/desktop/app/controllers/application.js

@@ -1,6 +1,7 @@
 import Controller from '@ember/controller';
 import { inject as service } from '@ember/service';
 import config from '../config/environment';
+import { computed } from '@ember/object';
 
 export default class ApplicationController extends Controller {
   // =services
@@ -10,4 +11,17 @@ export default class ApplicationController extends Controller {
   // =attributes
 
   notifyTimeout = config.notifyTimeout;
+
+  // =attributes
+
+  /**
+   * Display OS window actions (minimize, fullscreen, close) for
+   * Windows and Linux as OS frame/shell is disable.
+   * Does not apply to MacOS.
+   * @type {boolean}
+   */
+  @computed('isMacOS')
+  get isFrameless() {
+    return !this.isMacOS;
+  }
 }

ui/desktop/app/routes/application.js

@@ -32,13 +32,10 @@ export default class ApplicationRoute extends Route {
 
   /**
    * Add OS config on controller.
-   * Display OS window actions (minimize, fullscreen, close) for
-   * Windows and Linux. Not enabled for MacOS.
    */
   async setupController(controller) {
     controller.set('isMacOS', await this.ipc.invoke('isMacOS'));
     controller.set('isWindowsOS', await this.ipc.invoke('isWindowsOS'));
-    controller.set('showWindowActions', !controller.isMacOS);
   }
 
   // =actions

ui/desktop/app/templates/application.hbs

@@ -1,7 +1,7 @@
 {{page-title (app-name)}}
 
 <Rose::Layout::Global
-  class='{{if this.isWindowsOS ' layout-scroll'}}'
+  class='{{if this.isFrameless ' layout-scroll'}}'
   as |layout|
 >
 
@@ -19,7 +19,7 @@
       {{/if}}
 
       <header.utilities as |utilities|>
-        {{#if this.showWindowActions}}
+        {{#if this.isFrameless}}
           <Rose::Button
             @iconOnly='flight-icons/x-16'
             @style='warning'