Question: How to add additional styles to window style when it already using a style like in below?

```
    <Style x:Key="MyWindowStyle" TargetType="Window">
        <Setter Property="Control.Background" Value="PaleGreen"/>
        <Setter Property="Window.Title" Value="Styled Window"/>
    </Style>

```

My main window is:

```
<Window x:Class="Binding.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:Binding"
        mc:Ignorable="d"
        Style="{StaticResource MyWindowStyle}"
        Title="MainWindow" Height="450" Width="800">   
    <StackPanel>
        <Label  Content="Test Window" />
    </StackPanel>
</Window>

```

So I want to use `MyWindowStyle` but say I also want to add additional styles like adding the following:

```
        <Setter Property="BorderThickness" Value="3"/>
        <Setter Property="BorderBrush" Value="Red"/>

```

How do I do that? I can't figure out the syntax.

Answer: 
Problem is that when you use `StaticResouce` the resource has to be initialized before the usage.

In your case you have the resource inside the window therefor it is not initialized before the window is initialized.

Use `DynamicResource` instead and it will work:

```
<Window x:Class="Binding.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:local="clr-namespace:Binding"
    mc:Ignorable="d"
    Style="{DynamicResource MyWindowStyle}"
    Title="MainWindow" Height="450" Width="800">   

<Window.Resources>
    <Style x:Key="MyWindowStyle" TargetType="{x:Type Window}">
        <Setter Property="Control.Background" Value="PaleGreen"/>
        <Setter Property="Window.Title" Value="Styled Window"/>
        <Setter Property="BorderThickness" Value="3"/>
        <Setter Property="BorderBrush" Value="Red"/>
    </Style>
</Window.Resources>

   <StackPanel>
      <Label  Content="Test Window" />
   </StackPanel>
</Window>

```

See more [here](https://www.tutorialspoint.com/wpf/wpf_resources.htm) about WPF Resources.
You can define MyWindowStyle2 and use it.

```
<Style x:Key="MyWindowStyle2" TargetType="Window" BasedOn="{StaticResource MyWindowStyle}">
    <Setter Property="BorderThickness" Value="3"/>
    <Setter Property="BorderBrush" Value="Red"/>
</Style>

```

Or
[here](https://stackoverflow.com/questions/16096/how-to-apply-multiple-styles-in-wpf)