In revision 2583, I added the XamlBinding and WPF Designer to the setup of SharpDevelop 3.0.

XamlBinding is a language binding that integrates .xaml files into SharpDevelop's code-completion infrastructure.
Here is an example of SharpDevelop showing a tool tip for a property in a .xaml file:

A window in .xaml is a partial class: one part is generated from the .xaml file, the other is the user code. If the xaml file specifies a name for an element, the compiler will generate a field that can be used by the user code. XamlBinding adds code-completion support for such fields:

As you can see in the "Search Results" window, "Find references" now searches for references in .xaml files. The "rename" refactoring will update both the XAML and C# code.

Finally, the WPF designer that I wrote earlier this year is now integrated in SharpDevelop. Here is a screen shot:

The designer replaces SharpDevelop's property grid with its own, WPF-based property grid. This property grid will provide support for editing attached properties and data binding in the future.

Unlike the Windows Forms designer, which is included in the .NET Framework and merely hosted by SharpDevelop (which isn't as easy as it sounds); the WPF designer is written from scratch. Thankfully WPF makes this a lot easier than writing a Windows Forms designer from scratch would be.

The WPF designer is still missing lots of features; I would welcome any help.

You can download preview builds of SharpDevelop 3.0 from our build server.