Visual Studio 2012 XAML designer does not show correct content when App.xaml in different assembly

Question

I'm moving a WPF application from VS 2010 to VS 2012.

I have a main executable which contains the App.xaml and a separate class library for all the WPF stuff. In VS2012 (SP3) the XAML designer does not show any styles which are in a MergedResourceDictionary defined in App.xaml, VS 2010 does...

For testing purposes I moved App.xaml to my class library. After that the VS 2012 designer showed everything correctly.

Since class libraries cannot contain an App.xaml this is not a solution.

Any ideas?

My App.xaml looks like the following:

<Application x:Class="MyApplication.App"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Startup="AppStartup">
<Application.Resources>
    <ResourceDictionary>
        <ResourceDictionary.MergedDictionaries>
            <ResourceDictionary Source="pack://application:,,,/OtherAssemblyName;component/Resources/Resource1.xaml" />
            <ResourceDictionary Source="pack://application:,,,/OtherAssemblyName;component/Resources/Resource2.xaml" />
        </ResourceDictionary.MergedDictionaries>
    </ResourceDictionary>
</Application.Resources>

Answer 1

Know this is an old question, but answering it for anyone who may face something similar in the future.

The safest way to accomplish this is to create a new ResourceDictionary file, and add the MergedResourceDictionaries in it.

Then reference that ResourceDictionary in your user control/pages/windows - all of them, since the

<UserControl.Resources>
    <ResourceDictionary Source="GlobalResources.xaml" />
<UserControl.Resources>