Tracking changes in C# interactive window

Question

VS now comes with an interactive window, but unlike running the raw CSI.EXE Roslyn process, Visual Studio adds IntelliSense and a few other features such as being able to load in the current project.

I want to write a VS plug-in that tracks all text editor changes in this window. Is this possible? What I'm looking for is something akin to PreviewKeyDown/PreviewTextInput WPF events. Can I get those on the C# interactive window and, if so, how?

Here's how far I got so far:

var dte = Shell.Instance.GetComponent<DTE>();
foreach (Window window in dte.MainWindow.Collection)
{
  if (window.Kind.ToUpper().Contains("TOOL"))
  {
    if (window.Caption == "C# Interactive")
    {
      WpfWindow wpfWindow = (WpfWindow)HwndSource.FromHwnd((IntPtr) window.HWnd).RootVisual;
      for (int i = 0; i < VTH.GetChildrenCount(wpfWindow); ++i)
      {
        // now what?
      }
    }
  }
}

Answer 1

Here is some code that will get an IWpfTextViewHost reference on the C# interactive Window. From there, you can have access to all text services from Visual Studio: Text lines, Text buffer, etc. (or you can hook directly on WPF's controls, which I don't recommend)

// get global UI shell service from a service provider
var shell = (IVsUIShell)ServiceProvider.GetService(typeof(SVsUIShell));

// try to find the C# interactive Window frame from it's package Id
// with different Guids, it could also work for other interactive Windows (F#, VB, etc.)
var CSharpVsInteractiveWindowPackageId = new Guid("{ca8cc5c7-0231-406a-95cd-aa5ed6ac0190}");

// you can use a flag here to force open it
var flags = __VSFINDTOOLWIN.FTW_fFindFirst;
shell.FindToolWindow((uint)flags, ref CSharpVsInteractiveWindowPackageId, out IVsWindowFrame frame);

// available?
if (frame != null)
{
    // get its view (it's a WindowPane)
    frame.GetProperty((int)__VSFPROPID.VSFPROPID_DocView, out object dv);

    // this pane implements IVsInteractiveWindow (you need to add the Microsoft.VisualStudio.VsInteractiveWindow nuget package)
    var iw = (IVsInteractiveWindow)dv;

    // now get the wpf view host
    // using an extension method from Microsoft.VisualStudio.VsInteractiveWindowExtensions class
    IWpfTextViewHost host = iw.InteractiveWindow.GetTextViewHost();

    // you can get lines with this
    var lines = host.TextView.TextViewLines;

    // and subscribe to events in text with this
    host.TextView.TextBuffer.Changed += TextBuffer_Changed;
}

private void TextBuffer_Changed(object sender, TextContentChangedEventArgs e)
{
    // text has changed
}

Note "Microsoft.VisualStudio.VsInteractiveWindow" assembly is not specifically documented but the source is open: http://sourceroslyn.io/#Microsoft.VisualStudio.VsInteractiveWindow