VisualBrush.Visual bug with fix.

[Pip1987]

Bug:
Cannot find governing FrameworkElement or FrameworkConntentElement for target element. referencing VisualBrush.Visual

Fix:
Give the VisualBrush a name on Line 21 in ModalControl/Themes/Generic.xaml.

Example:
<VisualBrush x:Name="visualBrush" Visual="{Binding ElementName=border}" />

Notes:
The error seems to have no actual effect on the display, so fix is not necessary.