Fixing Button resources

[dipeshmsft]

Fixes # #9886

Description

Button styles were using the common / Fluent brushes directly rather than Button's control brushes like ButtonBorderBrush, ButtonBorderBrushPointerOver, etc.

In this PR, I have fixed the Button styles to use the Button control brushes correctly.

Customer Impact

Developers will be able to modify the Button control brushes without affecting other controls.

Regression

No

Testing

Local testing

Risk

No

Microsoft Reviewers: Open in CodeFlow

[robert-abeo]

These should just re-use ControlElevationBorderBrush. I don't think there is any reason to duplicate this complicated Brush. Otherwise, it is duplicate code and any updates would then have to be done multiple places -- bad practice.

WinUI does the same: https://github.com/microsoft/microsoft-ui-xaml/blob/589ced40542b9b4de2fddf0e58a1e3eecd164e2f/src/controls/dev/CommonStyles/Button_themeresources.xaml#L26-L27

I would ALWAYS review WinUI when making these types of changes.

---

Edit: I believe the below syntax works in WPF. I spend more time with more modern XAML frameworks so this needs to be tested.

    <StaticResource
        x:Key="ButtonBorderBrush"
        ResourceKey="ControlElevationBorderBrush" />
    <StaticResource
        x:Key="ButtonBorderBrushPointerOver"
        ResourceKey="ControlElevationBorderBrush" />

[dipeshmsft]

I don't think that works, but let me give it a try.

[dipeshmsft]

I get the following error when I do the above. However, I have seen this syntax in other places, but the StaticExtension there is a subclass of StaticResourceExtension for that : https://github.com/Kinnara/ModernWpf/blob/master/ModernWpf/Markup/StaticResourceExtension.cs

After that they can use the above syntax.

[robert-abeo]

I'm not actually sure what is going on here. The existing StaticResourceExtensions has this constructor as well:

wpf/src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/StaticResourceExtension.cs

Lines 35 to 39 in a792086

	public StaticResourceExtension(
	object resourceKey)
	{
	ArgumentNullException.ThrowIfNull(resourceKey);
	_resourceKey = resourceKey;

Either way, this is useful functionality. Perhaps it is a good idea to support it in Vanilla WPF as well.

[dipeshmsft]

I was looking further, the error seems to be thrown by a Debug.Assert statement here :

wpf/src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/Markup/BamlRecordWriter.cs

Line 563 in a792086

Debug.Assert(!InStaticResourceSection, "We do not support x:Key within a StaticResource Section");

I don't know why this is here. I will open up an issue for this and try to find out what's the reasoning behind this.

By the way, would you know how this works ? Does it create a copy of the actual resource or is just a reference to the original resource ?

[robert-abeo]

Same comment as for ButtonBorderBrush, ButtonBorderBrushPointerOver -- re-use the pre-existing brushes.