To reproduce:
-add grid pane to the content panel
-add button to cell (0,0) (first col and first row)
-select the button and increase row span 2 times(using modify-grid pane - increase row span)
-select and remove last row using button "-" at layout panel
It's expected that GridPane at hierarchy panel becomes "GridPane: 2 x 2", but it's still "GridPane: 2 x 3"