An error occurred while saving the commentjvb commented
working on a small screen often means closing the preview-window very, very often (shortcut command-W on a mac).
this works ok, but if the main window is selected by mistake the file closes, instead of the preview window.
this is obviously extremely frustrating, especially with large files and takes minutes to properly close and re-open.
just offer a normal "do you really want to close this document" like any other app - problem solved.