Epoch 4.0 Changes
			 =================

This distribution constitutes the official release of Epoch 4.0.

Hardware/OS platforms we've tested with include the following:

   o Sparcstation, SunOS 4.1.1, R4 & R5
   o Sun3/60, SunOS 4.1.1, R5
   o HP9000s375, HPUX 7.0, R4
   o HP9000s720, HPUX 8.0, R4
   o NeXT, NeXTStep 2.0 , R4 (Co-Xist)
   o Encore Multimax, Umax 4.3, R4
   o IBM RS6000, AIX 3.1.5 and 3.2, R4
   o Intel 486, SYSVR4, R3
   o SGI IRIS Indigo, Irix 4.0.2

We additionally have reports of Epoch running on other platforms,
including (but not limited to):

   o MIPS under RISCOS
   o DECstations under Ultrix
   o Apollo under Domain/OS
   o Sparc, Solaris 2.0
   o Titan

Changes from Epoch 3.2 include:

1.  Minibuffer modes.

    It is possible to have the minibuffer in its own distinct screen
(non-local, traditional Epoch) or at the bottom of each edit screen
(local, traditional GNU Emacs).  In the case of local minibuffers,
text typed/displayed in the minibuffer is potentially synchronized in
*all* minibuffer windows; this behavior is configurable with the
variable epoch::synchronize-minibuffers.

    To select local minibuffers, either invoke Epoch with the
"-nm" flag (no minibuffer screen), or include the following in your
'.Xdefaults' file:

epoch.nonlocal.minibuf:		false

2.  Buttons -> Zones.

    Epoch 3.2's "buttons" have been renamed "zones" to avoid the name
clash with X button events.  The behavior of zones is otherwise
identical to that of buttons.  Elisp code written to require buttons
may still be run, by requiring a wrapper package.  This can be done
with:

	(require 'button)

    Elisp code may be converted to require zones by using the
convert-buttons package.  To use this, do a (require
'convert-buttons), then run the function convert-current-buffer on the
relevent buffer.  Be sure to rewrite the file, and byte-compile if
necessary.

3.  Style-based display.

    Attributes no longer exist.  In particular, references to
attributes in Elisp will be invalid.  Epoch zones now reference styles
directly.  The old primitives (reserve-attribute),
(set-button-attribute), (button-attribute), and (set-attribute-style)
have been replaced/superceded by (set-zone-style), and (zone-style).
An example of this is:

    (setq s (make-style))
    (set-style-foreground s "red")

    (setq b (make-button))
    (set-zone-style b s)
    (move-button b 5 18)

    The style used for displaying characters in a buffer is now
determined according to a style hierarchy:
	
    1. Zone style (if present, following the zone display rule)    
    2. Buffer-local styles (setting the buffer-local variable 
       buffer-style)
    3. Screen styles.

    Screen styles are set with the existing primitives such as (font),
(foreground), (background), and (cursor-color).

    Styles can be embedded in the Elisp variables mode-line-format and
default-mode-line-format, which define modeline appearance.  See the
file "contrib/love/mode-styles.el" for an example of this.

4.  Proportional font support.

    Epoch 4.0 supports proportional fonts and lines with fonts of
differing heights.  Fonts are specified with the existing
(epoch::font) primitive, and may be specified in styles
(set-style-font).  Note that with proportional fonts, text using TABs
and containing alligned columns will not display as expected with
fixed-width fonts.

    Screen geometry specifications are in characters, based on the
base font for the screen.  (Epoch 4.0 is therefore compatible with
'.Xdefaults' settings from Epoch 3.2.)

    Emacs windows under Epoch now specify their dimensions in pixels
rather than characters.  Character dimensions are calculated based on
fonts used, and will not necessarily be constant.  New functions
returning pixel values are:

    (window-pixheight)
    (window-pixwidth)
    (window-pixedges)

    Existing Emacs functions still exist and return calculated
dimensions in character values:

    (window-height)
    (window-width)
    (window-edges)

    Additionally, functions to change window sizes or to split windows
will still take character arguments.

    Existing GNU Emacs packages should behave as expected if no
proportional fonts or fonts of differing heights are used; otherwise
things may be strange.  
        
5.  Mouse maps
	
    Epoch-4.0 mouse support is based on Ken Laprade's mouse package
for 3.2, so there is support for detecting mouse presses, etc. on
window modelines, etc.

    Mouse and motion event data is now passed to the Elisp event code
as pixel data rather than characters.  Key functions for using this
data are:

    (query-mouse)
    (query-pointer)
    (coordinates-in-window-p)
    (coords-to-point)

6.  Selection Support

    Cutting and pasting between Epoch and other X clients is now done
using the Selection mechanism.  By default, this uses the PRIMARY
selection; this will enable pasting with most R4 and later clients.
Some clients instead use the CLIPBOARD selection; Epoch can support
this by changing the variable epoch::selection-atom.

7.  .Xdefaults

    Epoch no longer reads the $HOME/.Xdefaults file upon startup; it
assumes that Epoch resources are in the X server's resource database.
This behavior can be overridden by the "-ud" flag, which forces Epoch
to read the .Xdefaults file directly.

Converting Elisp Code
---------------------
    As mentioned in section 2, attributes no longer exist.  The basic
changes required to Epoch 3.2 Elisp packages to run under Epoch 4.0
are:

    Typical Epoch 3.2 code:

    (defvar foo-attribute (reserve-attribute))
    (defvar foo-style (make-style))
    ...
    (set-attribute-style foo-attribute foo-style)
    (add-button start end foo-attribute)

    Corresponding Epoch 4.0 code:
	
    (defvar foo-style (make-style))
    ...
    (add-zone start end foo-style)
	
    ==> Note that all other reference to attribute functions are also
deleted.

    ==> Note that the ability to have buffer-local "attributes" is not
lost; the variable corresponding to a particular style can be made
buffer-local, with the values being separate styles in desired
circumstances.