WPF DatePicker Background Fix
There is an interesting issue with the DatePicker, and that is, for whatever reason Microsoft had, when you set the Background of
the control,
it only partially sets the Background. The center of the DatePicker
remains a color of white. Not exactly what one would expect. Below is a picture,
the top one is probably closer to what you would expect if you set the
background to a gold color, the second textbox is what you actually get when you set
the background to a gray.

The XAML for these controls looks like the following:
<DatePicker Name="datePicker1" Background="#FFC000"/>
<DatePicker Name="datePicker2" Background="#A6A6A6" />
I found a little trick that will more completely fill the background from the code-behind. In the constructor of the code-behind, I added
the following code for the first DatePicker control:
datePicker1.Loaded += delegate
{
var textBox1 = (TextBox)datePicker1.Template.FindName("PART_TextBox", datePicker1);
textBox1.Background = datePicker1.Background;
};