Type-system relationship between HasRaw*Handle and Has*Handle traits

[madsmtm]

Should there be a type-system relationship between these?

I think it would make sense to make the normal handles subtraits of the raw handles, i.e. trait HasWindowHandle: HasRawWindowHandle { ... }?

Or maybe we should do a blanket impl<T: HasWindowHandle> for HasRawWindowHandle {}, or vice-versa?

[madsmtm]

Related: What is the value even in having two traits? Is it just that way because we're yet unsure of the design?

I think it'd make sense to combine them into a single HasWindowHandle/HasDisplayHandle trait.

[notgull]

This change would make the semver trick hard to do... but #136 would already make it impossible so why not just go full ham?

I've often compared the difference between HasRawWindowHandle and HasWindowHandle to the difference between AsRawFd and AsFd in the standard library. However, I struggle to think of a use case where a type would implement HasRawWindowHandle and not HasWindowHandle. The standard library has to keep AsRawFd forever to avoid a breaking change, but we don't.

I would be in favor of just merging the traits.

[madsmtm]

I think the semver trick is basically already impossible, see #125 (comment).