Windows 10 developers: Microsoft's Project Reunion just gained this new tool

Microsoft unveils MRT Core resource loader for Project Reunion, its effort to fix problems with Win32 and UWP apps.
Written by Liam Tung, Contributing Writer on

Microsoft has released Modern Resource Technology (MRT) Core, an open-source project that supports the company's efforts behind Project Reunion to resolve conflicts between Win32 and Universal Windows Platform (UWP) apps. 

In May at its Build 2020 conference, Microsoft revealed Project Reunion as part of its plan to reverse errors it created with its 'Universal Apps/One Windows platform' from Windows 8 as the company fretted over the arrival of Apple's iPad and gave the world its doomed Metro user interface for touchscreens. 

In May Microsoft also released WinUI 3, a modern and native UI framework for Windows 10. WinUI 3.0 is Microsoft's next-generation user interface platform for Windows and Windows 10X, its OS for foldable PCs like the delayed Surface Neo.  

SEE: Cheat sheet: Windows 10 PowerToys (free PDF) (TechRepublic)

Windows 8 was meant to bridge Win32 app development with a new OS that could run modern apps and could launch them as full-screen apps or snapped alongside another app.

MRT Core, published by Microsoft on GitHub, is a new 'resource loader' that will be used with WinUi 3, according to Miguel Ramos, a program manager at Microsoft's engineering team for UWP, XAML and WinUI.        

"MRT was introduced to Windows in the Windows 8 timeframe and has evolved as the resource management system since that time," Microsoft says on its new GitHub repository for MRT. 

MRT Core provides support to build resource Package Resource Index (PRI) files and load resources from PRI files, Microsoft says. 

Project Reunion itself aims to give developers access to "existing Win32 and UWP APIs and make them available decoupled from the OS, via tools like NuGet".

It offers developers merged Win32 and UWP APIs, so they can add modern features like the Share panel to their desktop apps. It primarily relies on WinUI 3 and WebView2, another technology from Microsoft for integrating web content into an app. 

SEE: Seven Windows 10 annoyances (and how to fix them)

Recently added components to Project Reunion include the C++/WinRT, Rust/WinRT, and C#/WinRT libraries.

Microsoft plans on releasing a NuGet package on GitHub that will let app developers build PRI files from Visual Studio and use MRT Core APIs to load resources into their apps. It's also released APIs for the C programming language, its WinRT APIs and Microsoft Visual Studio files.  

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