[Wasm] MessageDialog does not show the Title or support Command customization

[jeromelaban]

I'm submitting a...

• Bug report

Current behavior

• A MessageDialog created with a title does not appear in the browser.
• A MessageDialog with more than one command does not appear in the browser.
• A MessageDialog with a customized command label does not appear the browser.

Expected behavior

• The title should appear.
• More than one command should be possible.
• The label of a command should be customizable.

Minimal reproduction of the problem with instructions

See https://github.com/nventive/Uno/blob/aaa4238952fca2a23e5b3f95ea22c5d933133e0e/src/Uno.UWP/UI/Popups/MessageDialog.wasm.cs#L19 and https://docs.microsoft.com/en-us/uwp/api/windows.ui.popups.messagedialog

Environment

Nuget Package: 1.43.1

Package Version(s): 

Affected platform(s):
- [ ] iOS
- [ ] Android
- [ ] WebAssembly
- [ ] Windows
- [ ] Build tasks

Visual Studio
- [ ] 2017 (version: )
- [ ] 2017 Preview (version: )
- [ ] for Mac (version: )

Relevant plugins
- [ ] Resharper (version: )

[ghuntley]

As per https://developer.mozilla.org/en-US/docs/Web/API/Window/alert and

As per https://docs.microsoft.com/en-us/uwp/api/windows.ui.popups.messagedialog

MesssageDialog is meant to be blocking of user interaction, have an optional title and can support up to 3 commands in desktop apps, or 2 commands in mobile apps. If no commands are specified, then a default command is added to close the dialog.

The current WASM implementation is a window.alert which does not allow for custom commands or a title thus I'm increasing the scope of this issue past title, to include custom commands.

Resolving this will mean either implementing ContentDialog first and making the experience similar to UWP or pushing this responsibility to shell or browser that's executing WASI.

[jeromelaban]

This feature can now be implemented using ContentDialog.

[MartinZikmund]

As MessageDialog use is discouraged by Microsoft (see https://docs.microsoft.com/en-us/uwp/api/Windows.UI.Popups.MessageDialog?view=winrt-20348), and ContentDialog is now fully supported, closing this issue.

MessageDialog Class (Windows.UI.Popups) - Windows UWP applications

Represents a dialog for showing messages to the user.