Steps to Reproduce:

1. install an extension that leverages custom editors (non-text based, like Luna paint or Hex editor)
2. open a folder
3. open a file in hex editor or luna paint
4. make the editor dirty
5. add a folder to the workspace
6. the extension host restarts
7. click on another editor
8. click back into the custom editor

=> the custom editor is gone and so is the data