Preserve ListBox multi-selections across InsertRow and RemoveRow

When a desktop ListBox has several rows selected (SelectionMode "Multiple"), calling InsertRow or RemoveRow from code does not preserve that selection. Inserting a row typically reduces the selection to a single row (the current/anchor row), and removing a row can clear the whole selection even when the removed row was not selected.

A multi-selection should survive row insertions and removals: rows that remain in the ListBox stay selected, and only a removed row is deselected.