private void Button_MouseEnter(object sender, MouseEventArgs e)
{
Grid g = (Grid)sender;
TextBlock tb = (TextBlock)(g.Children[1]);
var bc = new BrushConverter();
tb.Foreground = (Brush)bc.ConvertFrom("#cccccc");
Image collapseIcon = (Image)g.Children[0];
var imageUri = new Uri(@"pack://application:,,,/DynamoCoreWpf;component/UI/Images/expand_hover.png");
BitmapImage hover = new BitmapImage(imageUri);
// hover.Rotation = Rotation.Rotate180;
collapseIcon.Source = hover;
}