<StackPanel Name="myStackPanel" Margin="8">
  <TextBlock Name="myTextBlock" Margin="4" Text="Hello, world" />
</StackPanel>

// Return the general transform for the specified visual object.
GeneralTransform generalTransform1 = myStackPanel.TransformToVisual(myTextBlock);

// Retrieve the point value relative to the child.
Point currentPoint = generalTransform1.Transform(new Point(0, 0));