Currently, there appears to be an issue where the Undo Stack isn't correctly logging certain adjustments to an Elements positioning within a Grid's Rows and Columns.

See attached video.

Repro Steps:

1) Download, unzip, and open the attached Studio Project

2) Using the Selection Tool (V), select the GridSplitter present in the direct middle of the Stage, assigned to Row 1, Col1.

3) Click and drag the GridSplitter to a different Col/Row, and use the adorners to change its Span across those Rows/Columns

4) Actuate the Undo action (Ctrl+Z) to return the Page back to its original state when opened.

Observe how the GridSplitter does not return to the original position it was in when the Page was opened.

5) Close and re-open the Page.

Observe how now, the GridSplitter is in the expected middle-of-Page position.

Expected Results: There is parity between what is in the XAML, what is shown on-Stage, and what is displayed in an Element's Properties Panel.
Expected Results: The Undo Stack is capable of returning an Element to its previous position within a layout.