From the January 1992 GNU's Bulletin:
Version 19 will enter beta test late this year. Among its new features are: before and after change hooks, source-level debugging of Emacs Lisp programs, X selection processing (including clipboard selections), scrollbars, support for European character sets, floating point numbers, per-buffer mouse commands, X resource manager interfacing, mouse-tracking, Lisp-level binding of function keys, multiple X windows (`screens' to Emacs), a new input system, and buffer allocation, which uses a new mechanism capable of returning storage to the system when a buffer is killed.
The input stream is now a sequence of Lisp objects, instead of a sequence of characters. This allows a reasonable representation for mouse clicks, function keys, menu selections, etc.
Thanks go to Alan Carroll and the people who worked on Epoch for generating initial feedback to a multi-windowed Emacs, and to Eric Raymond for help in polishing the Emacs 19 Lisp libraries.
The June 1991 GNU's bulletin had this to say about future plans for Emacs:
Features being considered for later releases of Emacs include: associating property lists with regions of text in a buffer; multiple fonts, color, and pixmaps defined by those properties; different visibility conditions for the regions, and for various windows showing one buffer; hooks to be run if point or mouse moves outside a certain range; incrementally saving undo history in a file; static menu bars; and better pop-up menus.
Mention of this feature disappeared in the January 1992 GNU's bulletin:
Emacs 19 supports two styles of multiple windows, one with a separate screen for the minibuffer, and another with a minibuffer attached to each screen.
Mention of these two proposed features disappeared in the January 1991 GNU's bulletin: