Design-time-only background color in WPF?

Question

In WPF XAML there is the convenient DesignHeight and DesignWidth, for instance in code as

<UserControl ... d:DesignHeight="500" d:DesignWidth="500" ... />

which is great because I can build the layout with a representative, but not locked-in, control size.

However, I'm often building dark UIs, where labels and so forth need to be white, but my controls still need a transparent background color. This creates a design-time inconvenience because white seems to be the default background color for transparent controls in the designer, leading to unreadable white-on-white labels.

Is there a way or strategy for setting the design-time background color, with similar convenience as DesignHeight/DesignWidth?

Answer 1

There's an undocumented property d:DesignStyle of type Style that you can set on a user control. This style is only applied in the designer and is not used at runtime.

You use it like this:

<UserControl ... d:DesignStyle="{StaticResource MyDesignStyle}" />

Or like this:

<UserControl ...>
    <d:DesignerProperties.DesignStyle>
        <Style TargetType="UserControl">...</Style>
    </d:DesignerProperties.DesignStyle>
</UserControl>

Note however that any value set on the Style property (the one used at runtime) will also override the DesignStyle in the designer.