Get Absolute Position of element within the window in wpf

I think what BrandonS wants is not the position of the mouse relative to the root element, but rather the position of some descendant element.

For that, there is the TransformToAncestor method:

Point relativePoint = myVisual.TransformToAncestor(rootVisual)
                              .Transform(new Point(0, 0));

Where myVisual is the element that was just double-clicked, and rootVisual is Application.Current.MainWindow or whatever you want the position relative to.

Since .NET 3.0, you can simply use *yourElement*.TranslatePoint(new Point(0, 0), *theContainerOfYourChoice*).

This will give you the point 0, 0 of your button, but towards the container. (You can also give an other point that 0, 0)

Check here for the doc.

To get the absolute position of an UI element within the window you can use:

Point position = desiredElement.PointToScreen(new Point(0d, 0d));

If you are within an User Control, and simply want relative position of the UI element within that control, simply use:

Point position = desiredElement.PointToScreen(new Point(0d, 0d)),
controlPosition = this.PointToScreen(new Point(0d, 0d));

position.X -= controlPosition.X;
position.Y -= controlPosition.Y;

Add this method to a static class:

 public static Rect GetAbsolutePlacement(this FrameworkElement element, bool relativeToScreen = false)
    {
        var absolutePos = element.PointToScreen(new System.Windows.Point(0, 0));
        if (relativeToScreen)
        {
            return new Rect(absolutePos.X, absolutePos.Y, element.ActualWidth, element.ActualHeight);
        }
        var posMW = Application.Current.MainWindow.PointToScreen(new System.Windows.Point(0, 0));
        absolutePos = new System.Windows.Point(absolutePos.X - posMW.X, absolutePos.Y - posMW.Y);
        return new Rect(absolutePos.X, absolutePos.Y, element.ActualWidth, element.ActualHeight);
    }

Set relativeToScreen paramater to true for placement from top left corner of whole screen or to false for placement from top left corner of application window.