message: fix intermittent display issue of DataGrid and light theme
diff: <Setter Property="mah:ItemHelper.HoverBackgroundBrush" Value="{DynamicResource MahApps.Brushes.ThemeBackground}" />
  </Style>
  + <SolidColorBrush x:Key="MahApps.Brushes.DataGrid.Selection.Text" Color="{DynamicResource MahApps.Colors.ThemeForeground}" />
  <SolidColorBrush x:Key="MahApps.Brushes.DataGrid.Selection.Text.MouseOver" Color="{DynamicResource MahApps.Colors.ThemeForeground}" />
  <SolidColorBrush x:Key="MahApps.Brushes.DataGrid.Selection.Background" Color="Transparent" />
  <SolidColorBrush x:Key="MahApps.Brushes.DataGrid.Selection.Background.Inactive" Color="Transparent" />
  