fix(macOS): ignore Option/Alt and Command/Win keys as standalone input in TextBox

[Copilot]

On macOS (Skia), pressing Option or Command alone would insert symbols into a focused TextBox instead of being treated as a pure modifier.

What is the current behavior? 🤔

VirtualKey.Menu (Alt/Option) and VirtualKey.LeftWindows/VirtualKey.RightWindows (Command) pressed standalone produce unwanted character insertion in TextBox.

What is the new behavior? 🚀

These keys are now no-ops when pressed alone (same treatment as Control), while still functioning as modifiers in key combinations. KeyDown events continue to fire normally — only text insertion is suppressed.

Keys added to the no-op list in TextBox.skia.cs:

• VirtualKey.Menu, VirtualKey.LeftMenu, VirtualKey.RightMenu
• VirtualKey.LeftWindows, VirtualKey.RightWindows

Runtime test When_Alt_Or_Win_Key_Alone covers all five keys, asserting both that Text is unchanged and that KeyDown events still propagate.

PR Checklist ✅

Please check if your PR fulfills the following requirements:

• 📝 Commits must be following the Conventional Commits specification.
• 🧪 Added Runtime tests, UI tests, or a manual test sample for the changes have been added (for bug fixes / features) (if applicable)
• 📚 Docs have been added/updated which fit documentation template (for bug fixes / features)
• 🖼️ Validated PR Screenshots Compare Test Run results.
• ❗ Contains NO breaking changes

Other information ℹ️

Follows up on the original fix in #22014. Test naming uses Windows API terminology (Menu/Windows) rather than macOS-specific terms since Skia runs cross-platform.

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[Copilot]

Pull request overview

Fixes Skia TextBox text insertion when modifier keys (Option/Alt, Command/Windows) are pressed standalone, aligning behavior with other pure modifiers like Control while keeping KeyDown routing intact.

Changes:

• Treat VirtualKey.Menu/LeftMenu/RightMenu and VirtualKey.LeftWindows/RightWindows as standalone no-ops in TextBox.skia.cs (suppress text insertion).
• Add a Skia runtime test to assert standalone Alt/Windows keys don’t change Text and that KeyDown still fires.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/Uno.UI/UI/Xaml/Controls/TextBox/TextBox.skia.cs	Adds Alt/Windows virtual keys to the “standalone modifier no-op” switch to suppress character insertion.
src/Uno.UI.RuntimeTests/Tests/Windows_UI_Xaml_Controls/Given_TextBox.skia.cs	Adds a runtime test covering standalone Alt/Windows key behavior and KeyDown propagation.

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[Copilot]

When_Alt_Or_Win_Key_Alone repeats the same assert pattern for each key. Consider iterating over a small list of keys (and expected modifiers) to reduce duplication and make it easier to add/remove keys later.

Suggested change

	// Test Option/Alt keys
	SUT.SafeRaiseEvent(UIElement.KeyDownEvent, new KeyRoutedEventArgs(SUT, VirtualKey.Menu, VirtualKeyModifiers.None, unicodeKey: '\0'));
	await WindowHelper.WaitForIdle();
	Assert.AreEqual("hello world", SUT.Text);
	Assert.AreEqual(1, keyDownCount);
	SUT.SafeRaiseEvent(UIElement.KeyDownEvent, new KeyRoutedEventArgs(SUT, VirtualKey.LeftMenu, VirtualKeyModifiers.None, unicodeKey: '\0'));
	await WindowHelper.WaitForIdle();
	Assert.AreEqual("hello world", SUT.Text);
	Assert.AreEqual(2, keyDownCount);
	SUT.SafeRaiseEvent(UIElement.KeyDownEvent, new KeyRoutedEventArgs(SUT, VirtualKey.RightMenu, VirtualKeyModifiers.None, unicodeKey: '\0'));
	await WindowHelper.WaitForIdle();
	Assert.AreEqual("hello world", SUT.Text);
	Assert.AreEqual(3, keyDownCount);
	// Test Command/Windows keys
	SUT.SafeRaiseEvent(UIElement.KeyDownEvent, new KeyRoutedEventArgs(SUT, VirtualKey.LeftWindows, VirtualKeyModifiers.None, unicodeKey: '\0'));
	await WindowHelper.WaitForIdle();
	Assert.AreEqual("hello world", SUT.Text);
	Assert.AreEqual(4, keyDownCount);
	SUT.SafeRaiseEvent(UIElement.KeyDownEvent, new KeyRoutedEventArgs(SUT, VirtualKey.RightWindows, VirtualKeyModifiers.None, unicodeKey: '\0'));
	await WindowHelper.WaitForIdle();
	Assert.AreEqual("hello world", SUT.Text);
	Assert.AreEqual(5, keyDownCount);
	// Test Option/Alt and Command/Windows keys
	var keysToTest = new[]
	{
	VirtualKey.Menu,
	VirtualKey.LeftMenu,
	VirtualKey.RightMenu,
	VirtualKey.LeftWindows,
	VirtualKey.RightWindows
	};
	for (var i = 0; i < keysToTest.Length; i++)
	{
	SUT.SafeRaiseEvent(
	UIElement.KeyDownEvent,
	new KeyRoutedEventArgs(SUT, keysToTest[i], VirtualKeyModifiers.None, unicodeKey: '\0'));
	await WindowHelper.WaitForIdle();
	Assert.AreEqual("hello world", SUT.Text);
	Assert.AreEqual(i + 1, keyDownCount);
	}

[Copilot]

The test uses unicodeKey: '\0', but macOS Skia creates KeyEventArgs with unicode == 0 ? null : (char)unicode (see MacOSWindowHost.CreateArgs). That means a real standalone Option/Command press that produces unwanted insertion would have a non-zero unicode value, not \0. Consider using an arbitrary non-zero char (any visible symbol) to better match the regression being fixed, and set VirtualKeyModifiers.Menu/Windows to reflect the actual modifier flags for those keys on macOS.

Suggested change

	SUT.SafeRaiseEvent(UIElement.KeyDownEvent, new KeyRoutedEventArgs(SUT, VirtualKey.Menu, VirtualKeyModifiers.None, unicodeKey: '\0'));
	await WindowHelper.WaitForIdle();
	Assert.AreEqual("hello world", SUT.Text);
	Assert.AreEqual(1, keyDownCount);
	SUT.SafeRaiseEvent(UIElement.KeyDownEvent, new KeyRoutedEventArgs(SUT, VirtualKey.LeftMenu, VirtualKeyModifiers.None, unicodeKey: '\0'));
	await WindowHelper.WaitForIdle();
	Assert.AreEqual("hello world", SUT.Text);
	Assert.AreEqual(2, keyDownCount);
	SUT.SafeRaiseEvent(UIElement.KeyDownEvent, new KeyRoutedEventArgs(SUT, VirtualKey.RightMenu, VirtualKeyModifiers.None, unicodeKey: '\0'));
	await WindowHelper.WaitForIdle();
	Assert.AreEqual("hello world", SUT.Text);
	Assert.AreEqual(3, keyDownCount);
	// Test Command/Windows keys
	SUT.SafeRaiseEvent(UIElement.KeyDownEvent, new KeyRoutedEventArgs(SUT, VirtualKey.LeftWindows, VirtualKeyModifiers.None, unicodeKey: '\0'));
	await WindowHelper.WaitForIdle();
	Assert.AreEqual("hello world", SUT.Text);
	Assert.AreEqual(4, keyDownCount);
	SUT.SafeRaiseEvent(UIElement.KeyDownEvent, new KeyRoutedEventArgs(SUT, VirtualKey.RightWindows, VirtualKeyModifiers.None, unicodeKey: '\0'));
	SUT.SafeRaiseEvent(UIElement.KeyDownEvent, new KeyRoutedEventArgs(SUT, VirtualKey.Menu, VirtualKeyModifiers.Menu, unicodeKey: 'x'));
	await WindowHelper.WaitForIdle();
	Assert.AreEqual("hello world", SUT.Text);
	Assert.AreEqual(1, keyDownCount);
	SUT.SafeRaiseEvent(UIElement.KeyDownEvent, new KeyRoutedEventArgs(SUT, VirtualKey.LeftMenu, VirtualKeyModifiers.Menu, unicodeKey: 'x'));
	await WindowHelper.WaitForIdle();
	Assert.AreEqual("hello world", SUT.Text);
	Assert.AreEqual(2, keyDownCount);
	SUT.SafeRaiseEvent(UIElement.KeyDownEvent, new KeyRoutedEventArgs(SUT, VirtualKey.RightMenu, VirtualKeyModifiers.Menu, unicodeKey: 'x'));
	await WindowHelper.WaitForIdle();
	Assert.AreEqual("hello world", SUT.Text);
	Assert.AreEqual(3, keyDownCount);
	// Test Command/Windows keys
	SUT.SafeRaiseEvent(UIElement.KeyDownEvent, new KeyRoutedEventArgs(SUT, VirtualKey.LeftWindows, VirtualKeyModifiers.Windows, unicodeKey: 'x'));
	await WindowHelper.WaitForIdle();
	Assert.AreEqual("hello world", SUT.Text);
	Assert.AreEqual(4, keyDownCount);
	SUT.SafeRaiseEvent(UIElement.KeyDownEvent, new KeyRoutedEventArgs(SUT, VirtualKey.RightWindows, VirtualKeyModifiers.Windows, unicodeKey: 'x'));

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