Colors the background of a control.

ColorBackground

        public static IEnumerable<IContentItemPresenter> GetAssociatedPresenters(this IContentItem contentItem)
        {
            var internale = contentItem as IContentItemInternal;
            if (internale == null)
                return new List<IContentItemPresenter>();
            return internale.AssociatedPresenters;
        }
        
        
        public static void SetBackground(this IContentItemPresenter presenter, Color color)
        {
            if (presenter.Visual != null)
            {
                Control el = presenter.Visual as Control;

                //{System.Windows.Controls.Primitives.date}
                TextBox tb = FindControlByType<TextBox>(el);

                if (tb != null)
                {
                    Border tbContent = FindControlByType<Border>(tb);
                    if (tbContent != null)
                    {
                        tbContent.Background = new SolidColorBrush(color);
                    }
                }
                
                if (el is DateTimePickerVisual)
                {
                    TimeUpDown tu = FindControlByType<TimeUpDown>(el);
                    TextBox tbo = FindControlByType<TextBox>(tu);
                    Grid gr = FindControlByType<Grid>(tbo);
                    Border bo = FindControlByType<Border>(gr);
                    bo.Background = new SolidColorBrush(color); 
                } 
            }
        }

        private static T FindControlByType<T>(DependencyObject container) where T : DependencyObject
        {
            return FindControlByType<T>(container, null);
        }

        private static T FindControlByType<T>(DependencyObject container, string name) where T : DependencyObject
        {
            T foundControl = null;

            //for each child object in the container
            for (int i = 0; i < VisualTreeHelper.GetChildrenCount(container); i++)
            {
                //is the object of the type we are looking for?
                if (VisualTreeHelper.GetChild(container, i) is T && (VisualTreeHelper.GetChild(container, i).GetValue(FrameworkElement.NameProperty).Equals(name) || name == null))
                {
                    foundControl = (T)VisualTreeHelper.GetChild(container, i);
                    break;
                }
                //if not, does it have children?
                else if (VisualTreeHelper.GetChildrenCount(VisualTreeHelper.GetChild(container, i)) > 0)
                {
                    //recursively look at its children
                    foundControl = FindControlByType<T>(VisualTreeHelper.GetChild(container, i), name);
                    if (foundControl != null)
                        break;
                }
            }

            return foundControl;
        }