Its not just embedded NULs, its that files may not be UTF-8 encoded. How will Scintilla display non-UTF-8 files when it is told they are UTF-8? Will it be useful? Will it crash? Even if the buffer is read only will navigation and other actions work on non-UTF8 contents? And plugins, to date our guarantee to them was that the buffer was UTF-8 and no NULs? IMO its a very niche use-case that opens up a very wide problem space.