Introducing Eto.Forms – A cross platform UI for .NET

Creating desktop applications across multiple platforms has always been an elusive thing.  In .NET, there are a few options but none without drawbacks, most notibly is that the application will not look or behave like a native application for that platform, or that there are extra dependencies you must install/package with your app. Using the very excellent mono framework, one can certainly write C# and .NET code that run across all platforms, including Mac OS X, most flavours of Linux, and Windows. This does not mean, however, that your UI code will work across all platforms – that is a different beast.

Existing Frameworks

A few of the existing options for cross platform UI development (that I’ve seen people use) in .NET are GTK# and Windows Forms.

I’ve seen it time and time again; someone trying to wrangle an existing Windows Forms application to work on OS X.  It looks horrible and functions even worse, which is not surprising as mono’s implementation of Windows Forms is largely unmaintained and does all of its own control rendering.

GTK# does a decent job and is fairly well supported on all platforms, however it too does not look native on OS X and cannot easily be packaged with your app on Windows or OS X.

Multiple Implementations

Another alternative to using a cross platform toolkit is to write multiple versions of your UI, and share only the back end logic of your code. This is one of the better ways of getting a real native experience on each platform, but requires a lot of work if your UI is complex or has a lot of UI-specific logic. Ideally, if your interface will be similar across platforms, you should be able to share the code.

Here is a (simple) comparison of UI Frameworks for .NET:

.NET Desktop UI Frameworks 
Framework Platform Support Extra dependencies* Native on all Platforms?
GTK# All GTK# installer for Windows, Mono framework for OS X No
Windows Forms Windows,
Linux/OSX: poor support
Mono on non-Windows platforms No
WPF Windows Only N/A N/A
Qyoto (QT) All, little usage QT on non-Linux platforms No
wxWidgets All wxWidgets on all platforms Yes
MonoMac OS X Only None N/A

*Extra dependencies that are typically not already on each platform

Enter: Eto.Forms

Eto.Forms, which is a new BSD licensed (commercial app friendly) open-source UI framework, provides a new way to build desktop applications in .NET.  You can write simple, clean code and then have that code run natively, with no extra dependencies that wouldn’t already be available on each platform. Instead of choosing a framework above, you can target them all! (or, well a good portion of them.) The platforms that Eto.Forms supports currently are:

  • Windows using Windows Forms or WPF
  • OS X using MonoMac (creates an .app bundle with no additional dependencies)
  • Linux using GTK# (which come pre-installed or easily installed on popular distros such as Ubuntu and OpenSUSE)
Let’s take a quick look at the Eto.Test application on each of these:

Use Native Power! Without the headache.

A typical drawback of using a cross platform framework is that you can’t necessarily take advantage of each platform’s capabilities. Since Eto.Forms is just an abstraction layer, all of the power of each platform can still be fully utilized if need be, by way of its built-in styles mechanism, by creating your own abstracted controls, or by wrapping your Eto.Forms shared code inside of an existing native app.

What does it all mean?

Of course, no framework is the be-all end-all of frameworks.  Eto.Forms is relatively new, thus there will be use cases that it does not support yet.  Being open source you have the advantage that you can add any functionality as required, though a full compliment of typical controls are already fully functional on all platforms. This means you can create apps that look and work great on all platforms, with one set of code.

Start using & contributing!

Check out the Eto.Forms github page and wiki here: You can find support for Eto.Forms on google groups, or chat with other Eto.Forms developers on IRC.

7 thoughts on “Introducing Eto.Forms – A cross platform UI for .NET

  • Well there is a new player in the C# cross-platform UIs – NOV ( – the first C# based presentation layer for .NET. It runs even in Silverlight, which is something that GTK for example will never do. It is also the first portable GUI with integrated advanced typography – NOV rocks.

    • Problem with NOV is that it currently does not support Linux or Mac desktop so you can’t create cross platform apps right now. Eto.Forms supports WinForms, WPF, OS X, and GTK right now and is open source to boot.

  • That’s really good news, thank you for doing this work!
    I was looking for a cross platform, while easy to (manually) use GUI framework.
    and so far this looks really nice.

  • Awesome toolkit. Easy to use, clean api, clean design. Well thought through (e.g. the Style feature). This is very nice work, should be on top in the docs on mono-project and xamarin!

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