Display an Adorner over a WebBrowser control

Question

I'm using the System.Windows.Controls.WebBrowser for various things in my app and I've noticed that adorners are cut off when they are supposed to appear over a WebBrowser. I realize that the WebBrowser control is really a wrapper around a COM component and probably renders differently, but I wondered if anyone figured out how to solve this.

This is the problem I'm seeing. Here I have just a sample adorner that is supposed to draw a big red circle in the top corner of something (as a sample).

When I adorn the WebBrowser with this, I get this result:

I expect to see the full circle.

Here's the code for this worthless adorner, in case that is helpful:

public class SillyAdorner : Adorner
{
    public SillyAdorner(UIElement element) : base(element)
    {

    }
    protected override void OnRender(DrawingContext drawingContext)
    {
        drawingContext.DrawEllipse(new SolidColorBrush(Colors.Red), new Pen(), new Point(7, 7), 30, 30);
        base.OnRender(drawingContext);
    }
}

And here is how I apply it to the browser in the OnRender method of the host control:

    protected override void OnRender(DrawingContext drawingContext)
    {
        base.OnRender(drawingContext);            
        var layer = AdornerLayer.GetAdornerLayer(browser);
        layer.Add(new SillyAdorner(browser));
    }

Anyone have any hacks or workarounds for this?

Edit: I'm using .NET 4.0, if that makes a difference.

Edit #2: WebBrowser appears to inherit from HwndHost, which I've seen another question or two regarding adorners and hwndsources, but I'm not seeing anything that looks like I could implement it for the WebControl, but hopefully this is useful information for someone.

Answer 1

I don't think that will work with an Adroner, but you can float content over a WebBroswer control using a transparent Popup control. More details and a code sample can be found here.