wpf merge multiple styles into one style - wpf

Question

I have a UserControl that consists of a listview it looks like:
<UserControl
....
<UserControl.Resources>
<Style TargetType="Thumb">
<!-- Style Content -->
</Style>
<Style TargetType="GridViewColumnHeader">
<!-- Style Content -->
</Style>
<Style TargetType="{x:Type ScrollBar}">
<!-- Style Content -->
</Style>
<Style TargetType="{x:Type ScrollViewer}">
<!-- Style Content -->
</Style>
<Style TargetType="{x:Type ListViewItem}">
<!-- Style Content -->
</Style>
</UserControl.Resources>
<ListView Name="ListView1" >
<!-- ListViewContent -->
</Style>
</UserControl>
I have 3 of those userControls where the only thing that is different between them is the styles in <UserControl.Resources>. It makes no scene to have to create multiple controls that have the same functionality just because I need a different look and feel. What I want to do now is combine all the styles in <UserControl.Resources> into one style. If I manage to group all those styles into one I would be able to remove the 3 controls and change the style as:
<ListView Style={DynamicResource style1} ...
Currently if I do
<UserControl.Resources>
<Style x:Key="style1">
<!-- Place all styles in here -->
</Style>
</UserControl.Resources>
It does not work.
Edit
Thanks to iltzortz answer I now have:
Dictionary1.xaml:
<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Style TargetType="Grid">
<Setter Property="Background" Value="Green"></Setter>
</Style>
<SolidColorBrush x:Key="Foo" Color="Red"></SolidColorBrush>
</ResourceDictionary>
Dictionary2.xaml:
<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Style TargetType="Grid">
<Setter Property="Background" Value="Black"></Setter>
</Style>
<SolidColorBrush x:Key="Foo" Color="Orange"></SolidColorBrush>
</ResourceDictionary>
MyUserControl:
<UserControl x:Class="WpfApplication1.UserControl1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
d:DesignHeight="97" d:DesignWidth="91">
<UserControl.Resources>
<ResourceDictionary Source="Dictionary1.xaml" ></ResourceDictionary>
</UserControl.Resources>
<Grid >
<Ellipse Fill="{DynamicResource Foo}" />
</Grid>
</UserControl>
And I change resource dictionaries dynamically like this: switching wpf resource dictionaries at runtime

Answer 1

Add a resource dictionary to your application named e.g. common.xaml
and put your common styles there
then you can reuse it with:
<UserControl.Resources>
<ResourceDictionary Source="common.xaml"/>
</UserControl.Resources>

Answer 2

You can create 3 resource dictionaries and merge them at runtime. In my example code I used two resource dictionaries.
Example:
Dictionary1.xaml:
<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Style x:Key="btnStyle" TargetType="Button">
<Setter Property="Margin" Value="0,10,0,0" />
</Style>
</ResourceDictionary>
Dictionary2.xaml:
<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Style x:Key="btnStyle" TargetType="Button">
<Setter Property="Margin" Value="50,50,0,0" />
</Style>
</ResourceDictionary>
In the start of application you can set default style in App.xaml file:
<Application x:Class="Example.App"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
StartupUri="MainWindow.xaml">
<Application.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="/Dictionary1.xaml" />
</ResourceDictionary.MergedDictionaries>
</ResourceDictionary>
</Application.Resources>
</Application>
If you want to change style, you can merge resource dictionaries:
ResourceDictionary dict = new ResourceDictionary();
dict.Source = new Uri("\\Dictionary2.xaml", UriKind.Relative);
this.Resources.MergedDictionaries.Add(dict);
And now binding looks like this:
<Button Style="{DynamicResource btnStyle}" Content="Click me!" />
Now if you invoke code to merge resource dictionaries, button style will be automatically changed.