Question

Say i had a theme file Button.xaml for standard button.

By merged in application resource dictionary it can implicitly applied in application project designer.

But after i move Button.xaml to component project, the component project designer can not implicitly apply the theme file.

How can i make that theme file works implicitly in component project ?

Update:
the Themes.xaml as follow

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">

<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="pack://application:,,,/StyleLibrary;component/Themes/Shared.xaml" />
    <ResourceDictionary Source="pack://application:,,,/StyleLibrary;component/Themes/Button.xaml" />
    <ResourceDictionary Source="pack://application:,,,/StyleLibrary;component/Themes/ComboBox.xaml" />
...




<Application x:Class="ButtonStyleTest.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="pack://application:,,,/StyleLibrary;component/Themes.xaml"/> 
            </ResourceDictionary.MergedDictionaries> 
        </ResourceDictionary> 
    </Application.Resources> 
</Application> 

If i use merged Theme.xaml, the Button look normal in designer, but failed in runtime.
But if i merge Button.xaml, ComboBox one by one, it look normal for both design and runtime.

Answer 1

New example.

Say that you have a Library called StyleLibrary.
In this Library you have a ResourceDictionary called Button.xaml which looks like this

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <Style TargetType="{x:Type Button}" >
        <Setter Property="Width" Value="75" />
        <Setter Property="Height" Value="23" />
    </Style>
</ResourceDictionary>

In the Application we then add a reference to StyleLibrary and in App.xaml we add this.

<Application x:Class="ButtonStyleTest.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="pack://application:,,,/StyleLibrary;component/Button.xaml"/>
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>
    </Application.Resources>
</Application>

This style will apply in the Application and in the Libraries both in runtime and in designer.

To the left is my MainWindow. Is has one Button of its own, and then a UserControl from TestLibrary that has two Buttons. To the right is a Window from TestLibrary which contains one UserControl from TestLibrary, all Buttons seem to have the style applied.