Windows Store App - resource dictionary style issues - windows

Question

In a Windows Store App, I am unable to use a resource in one resource dictionary as the value of a property setter in a style of a second resource dictionary via a StaticResource binding.
Here is an example of what I'm trying to do:
Dictionary1.xaml
<ResourceDictionary
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<SolidColorBrush x:Key="SomeBrush" Color="Black" />
</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="SomeStyle" TargetType="Button">
<Setter Property="Foreground" Value="{StaticResource SomeBrush}" />
</Style>
</ResourceDictionary>
App.xaml
<Application
x:Class="TestApp.App"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Application.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="Common/StandardStyles.xaml"/>
<ResourceDictionary Source="Common/Dictionary1.xaml"/>
<ResourceDictionary Source="Common/Dictionary2.xaml"/>
</ResourceDictionary.MergedDictionaries>
</ResourceDictionary>
</Application.Resources>
</Application>
No matter what I do, this does not work. The app will not launch, instead throwing an unhandled exception to the effect of "a resource with key 'SomeBrush' cannot be found".
I've tried changing the order in App.xaml, playing with nested merged dictionaries, etc.
I have managed to get it to work by doing this, but this is not an option:
<ResourceDictionary
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="Dictionary1.xaml"/>
</ResourceDictionary.MergedDictionaries>
<Style x:Key="SomeStyle" TargetType="Button">
<Setter Property="Foreground" Value="{StaticResource SomeBrush}" />
</Style>
</ResourceDictionary>
At run time, App.Resources.MergedDictionaries is cleared and various resource dictionaries are dynamically loaded depending on various conditions. Both Dictionary1.xaml and Dictionary2.xaml are loaded independently of each other, and may contain different resources depending on those conditions, therefore merging them in this manner is not an option. They must be included in App.xaml at design time in order to support.... design.
Does anyone have any idea what is going on here? Is this a bug?
Thanks!

Answer 1

I believe I understand what's occurring here, I'll attempt to explain my view, hopefully it will make some sense.
From what I can see, after playing around and being able to replicate the issue you are seeing, it looks to me as though using the StaticResource keyword means that the key it's referring to needs to be available in the "scope" of the ResourceDictionary.
This would explain why your second attempt worked, because you have merged Dictionary1.xaml with Dictionary2.xaml, hence SomeBrush could be considered "in scope" and it would work.
Evidently, in the first scenario, the key defined in Dictionary1.xaml is considered "out of scope" for Dictionary2.xaml. But it would be considered "in scope" for the application.
I am basing a lot of this on what I have observed, but I have also found the following sentence in the ResourceDictionary and XAML resource references page on MSDN:
Within the scope of the ResourceDictionary, the dictionaries are checked for key uniqueness. However, that scope does not extend across different items in MergedDictionaries.

Answer 2

I had today a similar problem with a Universal App Project. The problem was, that the merged dictionaries need a Source-path with the ms-appx-protocol.
<ResourceDictionary Source="ms-appx:///Common/StandardStyles.xaml"/>
...
Does it solves your problem yet?