There are two ways to invoke GNU Emacs from QUI. The first way is by
selecting the Edit... item of the File pulldown menu in the
QUI window. The second way is by selecting the Edit Source item of
the File pulldown menu in the debugger window. In order to use
this second method of invoking GNU Emacs, you must already have a file
loaded in your Prolog program under QUI and it must be displayed in
the debugger source window. Selecting this menu item will invoke GNU
Emacs and place the cursor at the position of the file that defines
the predicate you are currently debugging. If you have invoked GNU
Emacs from the QUI window, a scratch buffer *qui-emacs* is displayed
on start up. This scratch buffer is needed to set up the communication
channels with QUI. Although the buffer is in qui mode, (which is the
minor mode in which all files with the extension .pl are placed) you
cannot use it as a normal prolog buffer as this buffer is not
associated with any file. Note that the *qui-emacs* buffer is
displayed only if you invoke the editor from the QUI main window. If
you invoke the editor from the debugger, the file that defines the
predicate you are debugging is displayed, not the *qui-emacs* buffer,
which is hidden.