How to set the style in WPF Window.Resources.

Question

I want to create multiple styles in the Window.Resources. Below is the code I tried, but it's not working:

<Window.Resources>
    <Style x:Key="StyleOne" TargetType="{x:Type Control}">
        <Setter Property="Control.Background" Value="Blue"></Setter>
        <Setter Property="Control.Height" Value="20"></Setter>
    </Style>
    <Style x:Key="StyleTwo" BasedOn="{StaticResource StyleOne}">
        <Setter Property="Control.Background" Value="Red"></Setter>
        <Setter Property="Control.Height" Value="20"></Setter>
    </Style>
</Window.Resources>
<Button Style="{StaticResource StyleOne}"></Button>
<Button Style="{StaticResource StyleTwo}"></Button>

It throws an error saying:

The property "Content" is set more than once.

Answer 1

This error has nothing to do with styles, the window can only contain one child (which sets the Content), use some container which can contain more than one child. e.g. a StackPanel or Grid.

<StackPanel>
     <Button .../>
     <Button .../>
</StackPanel>

(See also: Panels Overview)

Answer 2

set the target type for the second style

 <Style x:Key="StyleTwo"
           BasedOn="{StaticResource StyleOne}"
           TargetType="{x:Type Control}">
        <Setter Property="Control.Background"
                Value="Red"></Setter>
        <Setter Property="Control.Height"
                Value="20"></Setter>
    </Style>

put the buttons inside a stackpanel or Grid