Implement custom text context menus to fix crashes

[lhecker]

This works around a bug in WinUI where it creates a single context menu/flyout for text elements per thread, not per XamlRoot, similar to many other areas. Since the XamlRoot cannot change after creation, this means that once you've opened the flyout, you're locked into that window (= XAML root) forever. You can't open the flyout in another window and once you've closed that window, you can't open it anywhere at all.

Closes #18599

Validation Steps Performed

• Flies out right click in the
  • About dialog ✅
  • Search dialog ✅
  • Word delimiters setting ✅
  • Launch size setting ✅
• Across two windows ✅

[lhecker]

Is it possible to do this app-wide? This here fixes almost all occurrences of selectable text, thankfully.

[carlos-zamora]

Yeah, the only thing I can think of is doing it similar to above, but without an x:Key value, so it would apply it to all the textboxes. Like this:

<!--- BODGY: <reason> --->
<Style BasedOn="{StaticResource DefaultTextBoxStyle}"
       TargetType="TextBox">
   <Setter Property="ContextFlyout">
      <Setter.Value>
         <mtu:TextMenuFlyout />
      </Setter.Value>
   </Setter>
</Style>

At the bug bash today, I think Dustin also suggested trying to add it at the App.xaml layer or something like that (probably the XAML file you import WinUI 2).

[lhecker]

I think I may do this another time, if anything. My backlog of urgent work got a little long so I need to cut it short. 🙈

[carlos-zamora]

Does this fix #18246 too?

[carlos-zamora]

Yeah, the only thing I can think of is doing it similar to above, but without an x:Key value, so it would apply it to all the textboxes. Like this:

<!--- BODGY: <reason> --->
<Style BasedOn="{StaticResource DefaultTextBoxStyle}"
       TargetType="TextBox">
   <Setter Property="ContextFlyout">
      <Setter.Value>
         <mtu:TextMenuFlyout />
      </Setter.Value>
   </Setter>
</Style>

At the bug bash today, I think Dustin also suggested trying to add it at the App.xaml layer or something like that (probably the XAML file you import WinUI 2).

[carlos-zamora]

Double-checking: Just en-US?

[lhecker]

Yes, but the <OCResourceDirectory> key was missing.

[carlos-zamora]

Suggested change

	#pragma once
	// Copyright (c) Microsoft Corporation.
	// Licensed under the MIT license.
	#pragma once

Probably also worth adding the BODGY comment here and referencing the GH issue for historical reasons.

[carlos-zamora]

Suggested change

	#include "pch.h"
	// Copyright (c) Microsoft Corporation.
	// Licensed under the MIT license.
	#include "pch.h"

[carlos-zamora]

What about ComboBox with IsEditable=True?

[lhecker]

It seems like we don't use those yet. I wonder if it's worth adding support for that in advance...

[carlos-zamora]

Nice! Know if this fixes #18246 too?

[lhecker]

I'll wait for the Canary build and test (and close) it then. Theoretically it should be fixed.