Dan Field

Should we just mark `VoidCallback` as deprecated and convert all instances of it to `void Function()`?

It would achieve our goal of eliminating a `dart:ui` dependency where we don't want it, assuming we can live with having a `void Function()` signature instead of `VoidCallback`.

> @lrhn had spent some time thinking about `hashCode` somewhere in `dart:` – I think @kevmoo that's the issue I linked to above, #11617

The duplicated bug I linked is basically this one, although I found it even more confusing because I wasn't trying to refer to the variable explicitly - but this code...

Are you sure what you really want isn't `drawVertices`? Using that API you could performantly draw "pixels", moreso than using `drawRect` or `drawImage`.

The EmbeddedViews does have some kind of check about whether it's empty which it gets from `DisplayList::bounds` - I wonder what that's reporting in these cases?

MemoryFileSystem isn't optimized for performance. Its intended use is in testing frameworks. There's probably room to optimize it, but it's not something that any of the maintainers of this project...

Priority is generally given to bugs that affect the tests run by `flutter_tools`, which is the original reason this library was written.

`memoryFilesystemFile.readAsBytesSync()` shouldn't need to do any new allocations - the "file" is already basically just a `Uint8List` in memory. How would streams help here?

But in a `MemoryFileSystem`, the file is already just an in memory list of bytes, right? In a regular file system implementation that would make sense, but right now Dart...