XAML DynamicResource Not Working In Debug - wpf

Question

THE PROBLEM
I have a resource in a resource dictionary called RoundCorner:
<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:PMSpotlightSearch">
<Style x:Key="RoundCorner" TargetType="{x:Type Button}">
<Setter Property="HorizontalContentAlignment" Value="Center"/>
<Setter Property="VerticalContentAlignment" Value="Center"/>
<Setter Property="Padding" Value="1"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type Button}">
<Grid x:Name="grid">
<Border x:Name="border" CornerRadius="20" BorderBrush="Gainsboro" BorderThickness="2">
<Border.Background>
<RadialGradientBrush GradientOrigin="0.496,1.052">
<RadialGradientBrush.RelativeTransform>
<TransformGroup>
<ScaleTransform CenterX="0.5" CenterY="0.5" ScaleX="1.5" ScaleY="1.5"/>
<TranslateTransform X="0.02" Y="0.3"/>
</TransformGroup>
</RadialGradientBrush.RelativeTransform>
<GradientStop Offset="1" Color="#00000000"/>
<GradientStop Offset="0.3" Color="#FFFFFFFF"/>
</RadialGradientBrush>
</Border.Background>
<ContentPresenter HorizontalAlignment="Center" VerticalAlignment="Center" TextElement.FontWeight="Bold" />
</Border>
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="IsPressed" Value="True">
<Setter Property="Background" TargetName="border">
<Setter.Value>
<RadialGradientBrush GradientOrigin="0.496,1.052">
<RadialGradientBrush.RelativeTransform>
<TransformGroup>
<ScaleTransform CenterX="0.5" CenterY="0.5" ScaleX="1.5" ScaleY="1.5"/>
<TranslateTransform X="0.02" Y="0.3"/>
</TransformGroup>
</RadialGradientBrush.RelativeTransform>
<GradientStop Color="#00000000" Offset="1"/>
<GradientStop Color="#FF303030" Offset="0.3"/>
</RadialGradientBrush>
</Setter.Value>
</Setter>
</Trigger>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="BorderBrush" TargetName="border" Value="#FF33962B"/>
</Trigger>
<Trigger Property="IsEnabled" Value="False">
<Setter Property="Opacity" TargetName="grid" Value="0.25"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</ResourceDictionary>
I have loaded it into App.xaml:
<Application x:Class="PMSpotlightSearch.App"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:PMSpotlightSearch"
StartupUri="MainWindow.xaml">
<Application.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="RoundedCornerButton.xaml" />
</ResourceDictionary.MergedDictionaries>
</ResourceDictionary>
</Application.Resources>
</Application>
And it appears to work in my UserControl:
<UserControl x:Class="PMSpotlightSearch.SunkenButton"
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="450" d:DesignWidth="800">
<Border Width="75" Height="40" BorderThickness="1">
<Button Name="btnMain" Height="30" Width="73" Content="{Binding Name}" Visibility="Visible" FontSize="12" Foreground="LightGray"
Click="Button_Click" Background="#FF292929" Style="{DynamicResource RoundCorner}">
</Button>
</Border>
</UserControl>
This produces no errors, and shows up in the preview:
Beautiful, right? Here's how it looks in Debug mode:
Like a typical button...
Any suggestions?

Answer 1

The solution is to add the ResourceDictionary directly to the UserControl. Adding it to App.xaml is NOT enough:
<UserControl x:Class="PMSpotlightSearch.GLButton"
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="450" d:DesignWidth="800">
<UserControl.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="RoundCorner.xaml" />
</ResourceDictionary.MergedDictionaries>
</ResourceDictionary>
</UserControl.Resources>
<Border Width="50" Height="50" BorderThickness="1">
<Button Name="btnMain" Height="40" Width="40" Content="{Binding Name}" Visibility="Visible" FontSize="12" Foreground="LightGray"
Click="Button_Click" Background="#FF292929" Style="{DynamicResource RoundCorner}" />
</Border>
</UserControl>