I think you want to fix this function to call the appropriate function to match the compiler directive logic for the function declaration. Right now under version 20 the inherited ButtonFocusRect function call causes infinite recursion. I think under v20 you want to be calling the inherited ScaledButtonFocusRect?
{$IFDEF VER20}
function TcxACLookAndFeelPainter.ScaledButtonFocusRect(ACanvas: cxGraphics.TcxCanvas; R: TRect; AScaleFactor: TdxScaleFactor): TRect;
{$ELSE}
function TcxACLookAndFeelPainter.ButtonFocusRect(ACanvas: cxGraphics.TcxCanvas; R: TRect): TRect;
{$ENDIF}
begin
Result := inherited ButtonFocusRect(ACanvas, R);
end;