Visual Studio ContentDialog template creates dialog with old uwp styles (non WinUI 2.6)

Describe the bug If you create custom ContentDialog with VS template then you can see old UWP styles instead of new WinUI 2.6 styles.

Steps to reproduce the bug

1. Open Project
2. Create ContentDialog with VS template in separated file
3. Call ShowAsync:

new SomeContentDialogClass().ShowAsync();

1. See old ContentDialog styles.

Expected behavior ContentDialog must show new WinUI 2.6 styles

Screenshots

Custom ContentDialog

ContentDialog created with this code:

new ContentDialog().ShowAsync();

Version Info WinUI 2.6

NuGet package version: [Microsoft.UI.Xaml 2.6.0]

Windows app type:

UWP	Win32
Yes

Windows 10 version	Saw the problem?
Insider Build (xxxxx)
October 2020 Update (19042)	Yes
May 2020 Update (19041)
November 2019 Update (18363)
May 2019 Update (18362)
October 2018 Update (17763)
April 2018 Update (17134)
Fall Creators Update (16299)
Creators Update (15063)

Device form factor	Saw the problem?
Desktop	Yes
Xbox
Surface Hub
IoT

[crramirez]

Hello @StephenLPeters ,

More context: https://docs.microsoft.com/en-us/uwp/api/windows.ui.xaml.controls.contentdialog?view=winrt-20348#derived-controls-with-winui-styles

VisualStudio templates for create ContentDialog, creates a derived control without WinUI styles

Yesterday I had to add this to all of my dialogs that were created with VS templates

Regards

[StephenLPeters]

Sure, @anawishnoff FYI