Adapt TVargrid to Lazarus 1.8

Apparently original author make a fix for better scroll in TVarGrid. That fix works great until Lazarus 1.6 but in 1.8 the number of lines scrolled are incorrect.
This fix make that workaround conditional to Lazarus 1.6 or lower.

vargrid.pas

@@ -24,7 +24,7 @@
 interface
 
 uses
-  Classes, SysUtils, Grids, VarList, Graphics, Controls, LMessages, Forms, StdCtrls, LCLType, ExtCtrls,LazUTF8;
+  Classes, SysUtils, Grids, VarList, Graphics, Controls, LMessages, Forms, StdCtrls, LCLType, ExtCtrls,LazUTF8, LCLVersion;
 
 type
   TVarGrid = class;
@@ -127,9 +127,11 @@   TVarGrid = class(TCustomDrawGrid)
     procedure SetupCell(ACol, ARow: integer; AState: TGridDrawState; out CellAttribs: TCellAttributes);
     procedure DoOnCheckBoxClick(ACol, ARow: integer);
     procedure DoOnTreeButtonClick(ACol, ARow: integer);
+    {$IF LCL_FULLVERSION < 1080000}
     function  DoMouseWheelDown(Shift: TShiftState; MousePos: TPoint): Boolean; override;
     function  DoMouseWheelUp(Shift: TShiftState; MousePos: TPoint): Boolean; override;
     function  DoMouseWheel(Shift: TShiftState; WheelDelta: Integer; MousePos: TPoint): Boolean; override;
+    {$ENDIF}
     procedure DrawRow(aRow: Integer); override;
     function  GetCells(ACol, ARow: Integer): string; override;
     function  GetEditText(ACol, ARow: Longint): string; override;
@@ -1123,6 +1125,8 @@ procedure TVarGrid.DoOnTreeButtonClick(ACol, ARow: integer);
     FOnTreeButtonClick(Self, ACol - FixedCols, ARow - FixedRows, ColToDataCol(ACol));
 end;
 
+{$IF LCL_FULLVERSION < 1080000}
+
 function TVarGrid.DoMouseWheelDown(Shift: TShiftState; MousePos: TPoint): Boolean;
 begin
   Result := False;
@@ -1149,6 +1153,8 @@ function TVarGrid.DoMouseWheel(Shift: TShiftState; WheelDelta: Integer; MousePos
   end;
 end;
 
+{$ENDIF}
+
 constructor TVarGrid.Create(AOwner: TComponent);
 begin
   FRow:=-1;