ediff: Window and Frame Configuration
7.3 Window and Frame Configuration
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On a non-windowing display, Ediff sets things up in one frame, splitting
it between a small control window and the windows for buffers A, B, and
C. The split between these windows can be horizontal or vertical, which
can be changed interactively by typing ‘|’ while the cursor is in the
control window.
On a window display, Ediff sets up a dedicated frame for Ediff
Control Panel and then it chooses windows as follows: If one of the
buffers is invisible, it is displayed in the currently selected frame.
If a buffer is visible, it is displayed in the frame where it is
visible. If, according to the above criteria, the two buffers fall into
the same frame, then so be it—the frame will be shared by the two. The
same algorithm works when you type ‘C-l’ (‘ediff-recenter’), ‘p’
(‘ediff-previous-difference’), ‘n’ (‘ediff-next-difference’), etc.
The above behavior also depends on whether the current frame is
splittable, dedicated, etc. Unfortunately, the margin of this book is
too narrow to present the details of this remarkable algorithm.
The upshot of all this is that you can compare buffers in one frame
or in different frames. The former is done by default, while the latter
can be achieved by arranging buffers A, B (and C, if applicable) to be
seen in different frames. Ediff respects these arrangements,
automatically adapting itself to the multi-frame mode.
Ediff uses the following variables to set up its control panel
(a.k.a. “control buffer”, a.k.a. “quick help window”):
‘ediff-control-frame-parameters’
You can change or augment this variable including the font, color,
etc. The X resource name of Ediff Control Panel frames is ‘Ediff’.
Under X-windows, you can use this name to set up preferences in
your ‘~/.Xdefaults’, ‘~/.xrdb’, or whatever X resource file is in
use. Usually this is preferable to changing
‘ediff-control-frame-parameters’ directly. For instance, you can
specify in ‘~/.Xdefaults’ the color of the control frame using the
resource ‘Ediff*background’.
In general, any X resource pertaining the control frame can be
reached via the prefix ‘Ediff*’.
‘ediff-control-frame-position-function’
The preferred way of specifying the position of the control frame
is by setting the variable ‘ediff-control-frame-position-function’
to an appropriate function. The default value of this variable is
‘ediff-make-frame-position’. This function places the control
frame in the vicinity of the North-East corner of the frame
displaying buffer A.
The following variables can be used to adjust the location produced
by ‘ediff-make-frame-position’ and for related customization.
‘ediff-narrow-control-frame-leftward-shift’
Specifies the number of characters for shifting the control frame
from the rightmost edge of frame A when the control frame is
displayed as a small window.
‘ediff-wide-control-frame-rightward-shift’
Specifies the rightward shift of the control frame from the left
edge of frame A when the control frame shows the full menu of
options.
‘ediff-control-frame-upward-shift’
Specifies the number of pixels for the upward shift of the control
frame.
‘ediff-prefer-iconified-control-frame’
If this variable is ‘t’, the control frame becomes iconified
automatically when you toggle the quick help message off. This
saves valuable real estate on the screen. Toggling help back will
deiconify the control frame.
To start Ediff with an iconified Control Panel, you should set this
variable to ‘t’ and ‘ediff-prefer-long-help-message’ to ‘nil’
(
Quick Help Customization). This behavior is useful only
if icons are allowed to accept keyboard input (which depends on the
window manager and other factors).
To make more creative changes in the way Ediff sets up windows, you
can rewrite the function ‘ediff-setup-windows’. However, we believe
that detaching Ediff Control Panel from the rest and making it into a
separate frame offers an important opportunity by allowing you to
iconify that frame. The icon will usually accept all of the Ediff
commands, but will free up valuable real estate on your screen (this may
depend on your window manager, though).
The following variable controls how windows are set up:
‘ediff-window-setup-function’
The multiframe setup is done by the
‘ediff-setup-windows-multiframe’ function, which is the default on
windowing displays. The plain setup, one where all windows are
always in one frame, is done by ‘ediff-setup-windows-plain’, which
is the default on a non-windowing display (or in an xterm window).
In fact, under Emacs, you can switch freely between these two
setups by executing the command ‘ediff-toggle-multiframe’ using the
Minibuffer of the Menubar.
If you don’t like any of these setups, write your own function.
See the documentation for ‘ediff-window-setup-function’ for the
basic guidelines. However, writing window setups is not easy, so
you should first take a close look at ‘ediff-setup-windows-plain’
and ‘ediff-setup-windows-multiframe’.
You can run multiple Ediff sessions at once, by invoking Ediff
several times without exiting previous Ediff sessions. Different
sessions may even operate on the same pair of files.
Each session has its own Ediff Control Panel and all the regarding a
particular session is local to the associated control panel buffer. You
can switch between sessions by suspending one session and then switching
to another control panel. (Different control panel buffers are
distinguished by a numerical suffix, e.g., ‘Ediff Control Panel<3>’.)
Info Catalog
ediff: Quick Help Customization
ediff: Customization
ediff: Selective Browsing