[API] GetChildElementById doesn't work with SplitGrid

[jerone]

Current behavior

GetChildElementById is not able to find element for pane children within the SplitGrid.

It works for any other child.

How to reproduce it

public UIToolView View
{
    get
    {
        return new UIToolView(
            SplitGrid()
              .WithLeftPaneChild(Button("custom-id-1"))
              .WithRightPaneChild(DataGrid("custom-id-2"))
        );
    }
 }

var element1 = Gui.View.GetChildElementById("custom-id-1"); // null
var element2 = Gui.View.GetChildElementById("custom-id-2"); // null

Expected behavior

Expect element with id to be found within SplitGrid.

Affected DevToys kind

DevToys (app with GUI)

DevToys Version

Version 2.0-preview.5