Mobile Application Development Platforms: Gartner Magic Quadrant

Gartner Magic Quadrant:
Mobile Application Development Platforms

forms.kony.com/PPC-Q216-Gartner-MQ-2015-MADP_1GetMQReport.html

No Ionic on this chart, IBM is #1, SAP close behind... stange... 

Ionic: Advanced HTML5 Hybrid Mobile App Framework

So, What is IBM MobileFirst? | ANDREW TRICE

IBM Mobile Platform - Build and integrate mobile apps - US

Xamarin and IBM MobileFirst for the Mobile Enterprise - Xamarin

UrhoSharp: 3D game engine wrapper in C#

Xamarin is all about "wrappers for APIs".
Here is another interesting one, a 3D game engine wrapper in C#

UrhoSharp - Xamarin
"UrhoSharp is a cross-platform high-level 3D and 2D engine that can be used to create animated 3D and 2D scenes for your applications using geometries, materials, lights and cameras."
...
It is a .NET binding to the Urho3D engine and allows developers to write cross platform code that can target Android, iOS, Windows and Mac with the same codebase and can render to both OpenGL and Direct3D systems.
UrhoSharp is a game engine with a lot of functionality out of the box"

SkiaSharp: Cross-Platform 2D Graphics

Cross-Platform 2D Graphics with SkiaSharp | Xamarin Blog
"SkiaSharp, a cross-platform, high-performance 2D API for .NET developers available across mobile, desktops, and servers.
...

SkiaSharp provides a powerful C# API for doing 2D graphics powered by Google’s Skia library, the same library that powers Google Chrome, Firefox, and Android’s graphic stacks."

...

Skia gives us the same graphics output across all platforms, is actively maintained, and offers great features not found elsewhere, like filters and hardware accelerated graphics."

Given that .NET core does not yet have portable graphics library, and that Xamarin is now part of Microsoft, it could very well be that another part of Chrome browsers (besides of V8 JavaScript engine that is part of Node.js used in Visual Studio etc) can become part of Microsoft toolset.
That may in fact be very good solution, like Google's PDFium PDF rendering library is. 

Embrace and collaborate.

There are many more GUI tools portable across platforms, i.e. 

Qt - Mobile App Development

"Qt runs on Android, iOS, Windows Phone, Windows RT, BlackBerry10 and Sailfish"