Why is my button style not applied when declared in the resources of another style?

Question

I don't understand why this doesn't change the Background and Foreground while hovering the Button. It changes the CornerRadius of the Border tho.

ButtonStyle.xaml

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <Style TargetType="Button" x:Key="RoundedCorners">
        <Style.Resources>
            <Style TargetType="{x:Type Button}">
                <Style.Triggers>
                    <Trigger Property="IsMouseOver" Value="True">
                        <Setter Property="Background" Value="Red"/>
                        <Setter Property="Foreground" Value="Green"/>
                    </Trigger>
                </Style.Triggers>
            </Style>
            <Style TargetType="Border">
                <Setter Property="CornerRadius" Value="5"/>
            </Style>
        </Style.Resources>
    </Style>
</ResourceDictionary>

LoginView.xaml

<Button Height="50"
        Width="200"
        Style="{StaticResource RoundedCorners}">
    LOGIN
</Button>

What are `Primary` and `Black`? These are nowhere defined. Also, how is the Button defined? — Lennart, Jan 17 '23 at 08:33
Your inner Button style is not applied because there is an explicit Style already applied to the button. Move the Style triggers up to the outer style and it'll work — Corentin Pane, Jan 17 '23 at 08:45
Like this? If yes, it doesn't seem to work aswell. :( [Image](https://i.ibb.co/mqXyG6d/image.png) ` ` — Ednik, Jan 17 '23 at 08:51

Corentin Pane · Answer 1 · 2023-01-17T08:55:49.057

In WPF, an explicit Style set locally through Style={StaticResource StyleKey} takes precedence over an implicit style matched through a TargetType, as detailed here.

Hence, only the outer Style is applied to your Button because it's given a key and epxlicitly set.

To fix it, you should meger the inner Style into the keyed Style like this:

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <Style TargetType="Button" x:Key="RoundedCorners">
        <Style.Triggers>
            <Trigger Property="IsMouseOver" Value="True">
                <Setter Property="Background" Value="Red"/>
                <Setter Property="Foreground" Value="Green"/>
            </Trigger>
        </Style.Triggers>
        <Style.Resources>
            <Style TargetType="Border">
                <Setter Property="CornerRadius" Value="5"/>
            </Style>
        </Style.Resources>
    </Style>
</ResourceDictionary>

This will properly change the Foreground when you hover it. The Background will still not change, but that's an entire different problem.

Why is my button style not applied when declared in the resources of another style?

1 Answers1