retarget framework to .NET 4

Oct 13, 2014 at 2:08 PM
Very good help system
Good article, example working well

I tried to retarget framework to .NET 4, when click on MainWindow.xaml in Sora.HelpSystem.Editor project got error
Error 1 A 'Binding' cannot be set on the 'Document' property of type 'TextEditor'. A 'Binding' can only be set on a DependencyProperty of a DependencyObject.

Where I can find source code for Sora.Data.dll, Sora.FileSystem.dll and Sora.HelpSystem.dll to recompile those code for .NET Framework 4 ?