Question: [How can I show 2nd window in C++/WinRT Desktop (not UWP) with project reunion ?]

[vmx17]

Hi! I've been trying to find a way to show more than one window in C++/WinRT Desktop.
Is it possible or planned to implement in Project Reunion?
C++/WinRT + Project Reunion, what "Desktop" stand for?

There is a template named "[Experimental] Blank App. Packaged (WinUI 3 in Desktop)". I could add 2nd window "[Experimental] Blank Window (WinUI 3 in Desktop)". Though I could make it but there seems no way to show it. Should I use MFC?
at least, (like MainWindow);
	auto sub_win = make<SubWindow>();	// compile passed
	sub_win.Activate();			// no such method
does not work. I think there should be another way using hwnd or else. If possible, I want MDI style like in WnidowsForms.

According to "Overview and release notes: Windows UI Library 3 - Project Reunion 0.5 (March 2021)", in "Preview features"(https://docs.microsoft.com/en-us/windows/apps/winui/winui3/#preview-features) there are "Multi-window support in desktop apps", but on the other hand, in "Developer tools" on the same page says "Desktop apps support .NET 5 and C# 9, and must be packaged in an MSIX app". I'm confused. I could not find any examples that support multi-window desktop in C++/WinRT.

I'm using VisualStudio2019 16.11.0 Preview 2.0 with project reunion 0.8 preview on Windows 10 Pro 10.0.19043.

[StephenLPeters]

@llongley or @Austin-Lamb

[onnn]

I have the same problem. When I run that code, it compiles, and that method works. But the window flickers open and immediately closes.

[codendone]

Your code needs to hold a reference to the new window or it will get released and go away. This is something we're looking to fix as part of official multi-window support for 1.0.

[bpulliam]

I'm going to resolve this issue and track the issue moving forward with #6020.