When upgrading from StyleGrid 4.x then the following things have changed:

1)
     The CellGotSelected event was renamed to SelectionChanged and its 
     functionality changed so that it will now fire always when the selection
     changes (Also when it changes from something selected to
     nothing selected).

     So to migrate your project you need to:

     Check if your project is using the CellGotSelected, and if so then you 
     need to copy the code from there are paste it to the new SelectionChanged 
     event.
     Then you need to check the code that you put into the new event and make 
     sure that it takes into account that, now the event will also fire with
     no selection, that is with x = 0 and y = 0.

2)   The functionality of the KeyDown event changed.

     The way it was:
          If you returned false (or nothing):
               * Internal StyleGrid code got executed.
               * The event was routed to the control parent window.

          If you returned true:
               * Internal StyleGrid code did not get executed.
               * The event was routed to the control parent window.

      The way it works now in 4.5:
           If you return false (or nothing):
               * The event will be routed to the controls parent window
                 (except if its Left, Right, Up or Dowm key).

           If you return true:
               * The event will not be routed to the controls parent window.

           If you return false and set the CancelEventAction property
           to true then:
               * Internal StyleGrid code will not get executed.
               * The event will be routed to the control parent window.
           
           If you return true and set the CancelEventAction property
           to true then:
               * Internal StyleGrid code will not get executed.
               * The event will not be routed to the control parent window.
