Applying global styles to shadows

[kubaflo]

Description of Change

I have implemented 2 solutions for this. I don't know which one is better, so please let me know and I will keep the one you prefer.

Issues Fixed

Fixes #19560

Screen.Recording.2024-01-28.at.01.51.32.mov

[ghost]

Hey there @kubaflo! Thank you so much for your PR! Someone from the team will get assigned to your PR shortly and we'll get it reviewed.

[jsuarezruiz]

/azp run

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Azure Pipelines successfully started running 3 pipeline(s).

[cmartinezcxm]

Hey @kubaflo Thanks for the suggested PR, could you finish the merge of this?

[jsuarezruiz]

@kubaflo Could you rebase to fix the conflict?, thnx!

[kubaflo]

@jsuarezruiz rebased, and, thanks to it, only one change was needed to make it work :)

[StephaneDelcroix]

this doesn't look like the right fix. The problem probably comes from the Shadow isn't properly parented.
(parenting code was probably removed to 'fix' a memory leak, but we have a PR avoiding that leak)

[kubaflo]

@StephaneDelcroix I tried a solution with setting the parent visual element as a parent here:

maui/src/Controls/src/Core/VisualElement/VisualElement.cs

Lines 309 to 325 in 5d67531

	void NotifyBackgroundChanges()
	{
	var background = Background;
	if (background is ImmutableBrush)
	return;
	if (background != null)
	{
	SetInheritedBindingContext(background, BindingContext);
	_backgroundChanged ??= (sender, e) => OnPropertyChanged(nameof(Background));
	_backgroundProxy ??= new();
	_backgroundProxy.Subscribe(background, _backgroundChanged);
	OnParentResourcesChanged(this.GetMergedResources());
	((IElementDefinition)this).AddResourcesChangedListener(background.OnParentResourcesChanged);
	}
	}

but it didn't work :/

it's why I did the same thing as, for example, Span does

maui/src/Controls/src/Core/Span.cs

Lines 12 to 18 in 5d67531

	internal readonly MergedStyle _mergedStyle;
	/// <include file="../../docs/Microsoft.Maui.Controls/Span.xml" path="//Member[@MemberName='.ctor']/Docs/*" />
	public Span()
	{
	_mergedStyle = new MergedStyle(GetType(), this);
	}

[jsuarezruiz]

/azp run

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Azure Pipelines successfully started running 3 pipeline(s).