Currently, when the user is editing a cell and saves the document without leaving the edit mode first, the current value is not preserved in the saved document.
When pressing the File -> Save button in the ribbon, the Save dialog doesn't appear at all.
: Manually commit the change before saving. This workaround will also respect data validation:
var layer = ((NormalWorksheetEditorPresenter)radSpreadsheet.ActiveWorksheetEditor.ActivePresenter).UILayers.GetByName(WorksheetPredefinedUILayers.CellInput);
CellInputUILayer cellInputUILayer = (CellInputUILayer)layer;