All screenshots have been produced with LisaEm, which incorrectly draws scroll bars. This is an emulator issue and not an issue with the OS itself. Apart from this glitch, the emulator seems to be stable and usable.
It is tempting to view the Apple Lisa Office System as a prototype for the Macintosh; this is not, however the case, as beneath its slightly clunkier visual appearance, it is certainly a more sophisticated operating system than the Macintosh System was intially, and in some ways a more sophisticated operating system than any version of the Macintosh System that was ever released.
In addition to the Lisa Office System, the Lisa hardware could run Xenix, (rumouredly) CP/M, and with the addition of MacWorks and a video modification, the Macintosh System.
The Lisa Office System desktop
The Lisa Office System provides a spatial graphical user interface. The desktop is not a glorified folder, but a place for items in use to be put, more like the RISC OS pinboard. Icons can be placed here for quick reference by dragging them from a folder window; alternatively, open documents can be 'set aside', which puts them onto the desktop in their unsaved state ready to be opened again later, or to be 'put away' back into their folder.
Windows in the Lisa system are far more strongly identified with their originating icon than even on the Macintosh. The small icon corresponding to the originating icon is shown in the top left hand corner of each window, and to save changes and collapse the window back down to its originating icon, the small icon is double-clicked. This is equivalent to choosing 'Save changes and put away' from the 'File/Print' menu. When a document is opened, its document icon changes to the 'opened' state (on the Macintosh, this icon state could only be seen on folders and applications, because the one document to one window rule was abandoned).
The 'Walrus' document is open
The Lisa system is far more document-centred than the systems that replaced it; and it is fair to say that conceptually, the concept of an 'application' as a way of creating documents does not exist in the same way at all. Every document must have a corresponding icon within the folder heirarchy; so there cannot be any such thing as an untitled document which does not yet have an on-disc presence (as a side-effect of this, there is no 'Save As' or anything like it, as this would mean that a window could become attached to a different icon in the course of its lifetime).
By the same token, there is no such thing as an active application; when a document's window is frontmost, the appropriate menus for that document are displayed, but there is no application launch or application switch. It is worth noting that this is only possible because, unlike the Macintosh System, the Lisa Office System has true multi-tasking.
Documents must be created from a stationery pad (a concept which reappeared to some extent in System 7). Each 'tool' provides an initial blank stationery pad (named 'LisaWrite Paper', 'LisaDraw Paper' etc.), and any document can be turned into a stationery pad by selecting 'Make Stationery Pad' from the 'File/Print' menu while the document's icon is selected. When a stationery pad is double-clicked on, a new document icon is created next to it, named after the name of the stationery pad and the date. This metaphor extends to folders too; initially, the 'Empty Folders' pad is used to create folders, and any folder can become a stationery pad.
Creating a new LisaWrite document
As an aside, the Lisa system does not appear to have any issue with having multiple files with the same name; and, conceptually, why should it? If the icon is the window is the document, the file name is simply a label used as a memory aid by the user in association with the icon and the spatial position of the icon.
Documents and folders can be password-protected; the password is set from the 'Attributes of...' menu item in the 'File/Print' menu (which is the equivalent to the Macintosh's 'Get Info' item). When a potected document or folder is opened, the system will ask for the password before opening it.
"Attributes of LisaWrite Paper 09/07"
Opening a protected document
It is possible to have tools that are not associated with documents; two examples of this are the clock and the calculator. To launch these, their icons can be double-clicked; but to show that they are not documents, the resulting windows have a different style of title bar with solid corners and solid black when active. This is a convention that was carried over to the Macintosh.
If a document-centric tool is double-clicked on, then the tool tells you to tear off a piece of stationery.
Using the Lisa makes the choice of certain terminology in the Macintosh make more sense; the existence of the 'Put Away' menu item on the Macintosh to return an icon on the desktop to its original location is a feature for those who wish to use it in a Lisa-like fashion. Visually, the Lisa is less clear and well laid-out than the Macintosh; it feels considerably more cluttered, the icons are less ideographic and the fonts are less well-constructed. In terms of feel, however, the Macintosh feels less well-thought-through; it suffered greatly from being a single-tasking operating system, a constraint which must enforce a program-centric approach in user interaction with the system. By the time the Macintosh OS had gained some degree of multitasking with the MultiFinder, it was impossible to re-integrate the document model into the spatial interface; and in the MacOS X UI the spatial elements were effectively abandoned altogether.