Custom editor autosave menubar state not updated properly

Hi @mjbvz @jrieken, I've been catching up with the daily updates, thanks for them btw. While working on our stuff, I've been noticing some issues on VSCode. Probably they're known issues but I'm sharing here in case they've been missed somehow. I'm able to reproduce them on both our code and [this](https://github.com/mjbvz/vscode-extension-samples/tree/custom-editor-examples/custom-editor-sample) code. **Linux and Windows** - [File -> Auto Save] Auto save enabled: "Save" is not triggered if you quickly (less than 1s) close the editor after making a change. **Linux-only** - [File -> Auto Save] The "check" symbol is not shown when you enable "auto save" within the custom editor; however, the operation works. - [File -> Revert File] Sometimes the menu button is kept disabled when you start VSCode, even after changes. - [File -> Save All] Same behavior ^ - [File -> Save] Same behavior ^; Ctrl+S works. - [File -> Save As] Same behavior ^; Ctrl+Shift+S works. _note: the menu buttons become enabled when I open a text editor_ **Windows-only** - [File -> Revert File] Can't use; always disabled. Please let me know if you need any further information. _Originally posted by @caponetto in https://github.com/microsoft/vscode/issues/77131#issuecomment-620571200_