By default, in Spread WinForms 12, the date time functions and formulas used in worksheets return the serial numeric values as results.  

However, if a user uses the LegacyBehaviors.CalculationEngine, the date time functions and formulas will return DateTime values instead of the serial numeric values.       

By default, LegacyBehaviors.PropertyDefaults is turned off in V12. When this flag is turned off then there are some changes as compared with the older versions as described below-

1. Changes in default values for the following APIs
   

   FpSpread.AllowUserFormulas = true
   FpSpread.AllowDragDrop = true
   FpSpread.AllowDragFill = true
   FpSpread.AllowSheetMove = true
   FpSpread.AllowEditOverflow = true
   FpSpread.BorderCollapse = BorderCollapse.Collapse
   FpSpread.ResizeZeroIndicator = true
   FpSpread.TabStripPolicy = TabStripPolicy.Always   
   SheetView.SelectionPolicy =SelectionPolicy.MultiRange
   SheetView.AutoFilterMode = AutoFilterMode.EnhancedContextMenu
   SheetView.Protect = false and Cell.Locked = true (same with V11J but different from V10 and lower versions)

   
   
2. Changes during keyboard navigation
   
   Pressing the "F2" key will start editing with current cell value.
   Pressing "Backspace" key will start editing with empty editor.
   Pressing the "F4" key takes no effect.
   When a user presses an input key to start editing, the current cell value will be replaced by the pressed key.