Center the Header of the RadWindow
In order to allow the content in the header to be centered, you can set a UIElement (for example TextBlock) with HorizontalAlignment="Center" as the Header of the RadWindow. This is demonstrated in Example 1.
Example 1: Centering the Header of the RadWindow
Figure 1: Result from Example 1 in the Office2016 theme
Alternatively, you can also place the centered UIElement in the HeaderTemplate of the RadWindow.