Add scrollbar.showScrollbar

Fixes #5676

demo/client/client.ts

@@ -284,7 +284,7 @@ function createTerminal(): Terminal {
 
   const isWindows = ['Windows', 'Win16', 'Win32', 'WinCE'].indexOf(navigator.platform) >= 0;
   term = new Terminal({
-    scrollbar: { showArrows: true },
+    scrollbar: { showScrollbar: true },
     allowProposedApi: true,
     windowsPty: isWindows ? {
       // In a real scenario, these values should be verified on the backend

demo/client/components/window/optionsWindow.ts

@@ -123,6 +123,8 @@ export class OptionsWindow extends BaseWindow implements IControlWindow {
       'windowsPty',
     ];
     const nestedBooleanOptions: { label: string, parent: string, prop: string }[] = [
+      { label: 'scrollbar.showScrollbar', parent: 'scrollbar', prop: 'showScrollbar' },
+      { label: 'scrollbar.showArrows', parent: 'scrollbar', prop: 'showArrows' },
       { label: 'vtExtensions.kittyKeyboard', parent: 'vtExtensions', prop: 'kittyKeyboard' },
       { label: 'vtExtensions.kittySgrBoldFaintControl', parent: 'vtExtensions', prop: 'kittySgrBoldFaintControl' },
       { label: 'vtExtensions.win32InputMode', parent: 'vtExtensions', prop: 'win32InputMode' }