Miguel de Icaza’s report from the Game Developer Conference is upbeat, rightly so in my view as usage of Mono is continuing to build, not only in game development with Unity, a development tool that uses Mono as its scripting engine, but also for mobile development for Apple’s iOS with Monotouch and for Android with Monodroid. These mobile toolkits also give Mono a stronger business model; many sites use Mono for serving ASP.NET applications on Linux, but without paying or contributing back to the project.

Mono is an open source implementation of C# and Microsoft’s .NET Framework.

That said, it is interesting that Mono is still struggling with an issue that has been a problem since its first days: how to implement Microsoft’s GUI (Graphical User Interface) framework on other platforms. Mono does have Gtk# for Windows, Mac and Linux, but this does not meet the goal of letting developers easily port their Visual Studio client projects to Mono. There is also an implementation of Windows.Forms, but de Icaza mentions that “our Windows.Forms is not actively developed.”

Apparently many tools vendors asked the Mono team at GDC when Windows Presentation Foundation (WPF) would be implemented for Mono. WPF is the current presentation framework for Microsoft.NET, though there is some uncertainty about where Microsoft intends to take it. I remember asking de Icaza about this back in 2003, when the WPF framework was first announced (then called Avalon); he said it was too complex and that he did not plan to implement it.

This is still the case:

We have no plans on building WPF. We just do not have the man power to build an implementation in any reasonable time-frame.

That said, Mono has implemented Silverlight, which is based on WPF, and there are some signs that Microsoft might merge WPF and Silverlight. What would the Mono team do then?

Miguel de Icaza says:

Silverlight runs on a sandbox, so you can not really P/Invoke into native libraries, or host DirectX/Win32 content inside of it.
There are other things missing, like menubar integration and things like that.

Of course, this is no longer true on Windows: Platform Invoke is coming in Silverlight 5.

Perhaps the Mono team will knuckle down and implement Silverlight with desktop integration, which would be good for cross-platform Silverlight and compatibility with Microsoft .NET.

Then again, it seems to me that Mono is increasingly divergent from Microsoft .NET, focusing on implementing C# in places that Microsoft does not touch, such as the mobile platforms from Apple and Google.

That is actually a sign of health; and you can understand why the Mono team may be reluctant to shadow Microsoft’s every move with Silverlight and WPF.