wix4 cannot use Engine.Apple(null) albeiht wix3 supports it

[svg2003]

When calling Engine.Apply(IntPtr.Zero) (or null HWND), wix4 throws the exception.
In opposite, wix3 allow to do it and executes installation (or uninstallation) actions.

https://github.com/wixtoolset/wix/blob/develop/src/burn/engine/externalengine.cpp#L675

[barnson]

https://wixtoolset.org/docs/fourthree/faqs/#balutil-and-wixtoolsetmbacore-breaking-changes

[svg2003]

Thank you for promptly response.
However, it worked before without any issues. Please put yourselves in the shoes of toolset users when making breaking changes. There is a lot of code that needs to be switched from Wix3 to Wix4 due to various reasons. Dealing with every breaking change and finding a way to work around it in legacy code is a huge pain and risk for final product.

[barnson]

There were issues and the requirement for a valid window handle fixes those issues.

[svg2003]

Is it feasible for engine just to create empty hidden window if it's really required ?
Workaround probably would be the same, but all developers who is using API this way would need to invent it.

[barnson]

I don't know. If you want to investigate and propose a change, file an issue with the results here.