Thomas Becker's Free Software Utilities

PC Mode: Emulating Some Features of MS-Windows-Based Editors in GNU Emacs

Copyright (C) 1995 2000 2007 Thomas Becker


  1. Overview
  2. Important: Emacs Version Considerations
  3. Usage
  4. Download and Installation
  5. Feedback and Bug Reports
  6. PC Mode in Detail
  7. Customizing PC Mode


There are some features commonly found on MS-Windows-based editors that some people find desirable to have. For example, the action of the shift-arrow keys and the control-tab combination in MS-Windows-based editors is rather convenient. Also, the behavior of the cursor when scrolling in an MS-Windows-based editor is quite intuitive. PC Mode emulates some of these features in GNU Emacs.

PC mode is not the only package that emulates aspects of MS-Windows-based editors in GNU Emacs. There are other packages out there that do similar things. Most notably, there is pc-bindings-mode and pc-selection-mode. What my PC mode offers is a certain unique combination of features which I personally think are most desirable. Specifically, I am not aware of any other GNU Emacs package that offers my cursor behavior when scrolling, or my MS Visual Studio 8 style quick buffer selection via control-tab.

UsingPC mode also makes it easy for users of Microsoft products such as Microsoft Visual Studio to switch to GNU Emacs.

Emacs Version Considerations

I am using PC Mode with GNU Emacs 22. If you are running a more recent version of GNU Emacs, you're on your own. Since backward compatibility is not a feature of GNU Emacs, PC Mode may or may not work. If you are running GNU Emacs Version 21, you will have to install an earlier version of PC Mode. This earlier version can be found in a subdirectory named emacs21 in the distribution.


There is no need to study a lot of documentation concerning PC Mode. Just install it according to the instructions below, start using Emacs, and try the following key combinations (note the behavior of the cursor when scrolling):

  • arrow keys, home, control-home, end, control-end, and page up/down (with and without the shift key)
  • control-up-arrow and control-down-arrow
  • alt-up-arrow and alt-down-arrow
  • control-TAB and shift-control-TAB (with and without preceding control-u)
  • control-page-up and control-page-down (with two visible buffers)
  • M-% (with and without an active selection, and when a search has been performed earlier)

Download and Installation

PC mode can be downloaded from here. If you are using GNU Emacs 22, place the file pc-mode.elc in some directory DIR and add the lines

(load-file "DIR/pc-mode.elc")
(pc-mode 1)

to your Emacs initialization file. If you are still using GNU Emacs 21, then place the file pc-mode-21.elc in the directory DIR and add the lines

(load-file "DIR/pc-mode-21.elc")
(pc-mode 1)

to your Emacs initialization file. "DIR/" may of course be omitted if the .elc file is in a directory where Emacs looks for lisp files. Be sure to load the .elc file and not the .el file. It is customary but not necessary to put the .el file in the same directory as the .elc file.

Please note: Once PC Mode has been turned on, you must neither enable or disable competing or related packages such as pc-selection-mode or transient-mark-mode. Doing so will almost certainly override key bindings that PC Mode needs or otherwise interfere with the proper functioning of PC Mode.

Feedback and Bug Reports

Click to send feedback and bug reports concerning PC mode.

PC Mode in Detail

Selection, Mark, and Region

MS-Windows-based text editors start a new selection, that is, highlighted text, whenever the user moves the cursor or scrolls with the shift key pressed. Further cursor movement or scrolling with the shift key pressed will then extend or shrink the region.

The analog of the selection in GNU Emacs is the region, that is, the text between the point and the mark. Traditionally, the Emacs region is not highlighted. The only way to visualize it is to call exchange-point-and-mark, e.g., by pressing Ctl-x Ctl-x.

If transient-mark-mode and delete-selection-mode are turned on in Emacs, then the region behaves much more like the selection in an MS Windows editor. However, to start an active region (or selection in Windows speak), one still has to set the mark in the traditional way, e.g., by pressing Ctl-SPC. Ordinary cursor movement or scrolling will then extend or shrink the active region. To deactivate the region without any further effect, one must call keyboard-escape-quit, e.g., by pressing M-ESC ESC.

What PC mode does is to make the arrow keys, the page up/down keys, and the home and end keys behave as described above for MS-Windows-based editors.

There are a number of more sophisticated ways of moving the cursor under Emacs, e.g., Ctl-M-p (backward-list). One might consider having the same Windows-style behavior for these keys as well. However, PC mode currently does not do that. The reason is that a key combination such as Shift-Ctl-M-p does not seem to add any convenience. Moreover, there are environments that cannot even distinguish between Ctl-M-p and Shift-Ctl-M-p. To create an active region (a selection in Windows speak) with a key such as Ctl-M-p, you proceed as you normally would in transient mark mode: set the mark with Ctl-SPC, then move the cursor.

Quick Buffer Selection with Ctl-TAB

In PC mode, if you type Ctl-TAB or Shift-Ctl-TAB, you will be shown a no-frills buffer list. Special buffers that do not visit files such as *Completions* or *Help* are not shown, with the exception of the *Scratch* buffer. Ctl-TAB or down-arrow moves down in the buffer list, whereas Shift-Ctl-TAB or up-arrow moves up. To switch to the selected buffer, you must type TAB or RET. Any other key will abandon the buffer selection.

The choice of the window in which to show the newly selected buffer is governed by the following rules:

  1. If the selected buffer is already shown in one or more Emacs windows, then the nearest one of these (in Emacs' window order) is used.
  2. If the current buffer is a special buffer such as *Completions* or *Help*, then another window is used. This behavior is based on the assumption that buffers such as compilation buffers or debugging buffers are special output areas that should not be used for editing files.
  3. Absent any of the above considerations, the currently selected window is used.

If you precede the first Ctl-TAB (or Shift-Ctl-TAB, as the case may be) with a Ctl-u, then the buffer selection behaves like the emacs funtion switch-to-buffer-other-window (Ctl-4-b): the buffer that you have selected is always shown in another window.

Fixed Cursor Scrolling

When you scroll a buffer in Emacs, the cursor tries to stay at its current position in the text. (More precisely, in Emacs terminology, the point tries not to move.) This attempt to leave the cursor position unchanged in the text will of course not be successful for very long: soon, the cursor will end up at the top or bottom of the screen. If, for example, you have the cursor somewhere in the middle of the screen, then scroll up one or more screenfulls to look at something, then scroll back to where you were before, your cursor has moved to the top of the screen. There is no conceivable reason why you would want it there.

A more user-friendly way of handling the cursor upon scrolling (although it may seem counterintuitive at first) is to leave the physical cursor position on the screen unchanged. PC mode makes the page-up and page-down keys behave that way.

Another feature that is common in MS-Windows-based editors is to have control-up-arrow and control-down-arrow bound to scrolling by one line (smooth scrolling). PC mode provides that binding. Again, the cursor stays at its physical position on the screen. This kind of smooth scrolling with the cursor being fixed on the screen is particularly useful for looking at code indentation.

With smooth scrolling, I do sometimes find myself wanting the cursor to stay at its position in the text. Therefore, PC mode binds smooth scrolling with the cursor fixed in the text to alt-up-arrow and alt-down-arrow.

Finally, PC mode provides a way to parallel-scroll through the current buffer and the buffer in the next window. To try this, make two windows—the term "window" being used in the sense of Emacs here—on your screen and press control-page-up and control-page-down.

Query-Replace Defaults

When you perform a query-replace via M-% and the mark is active, that is, you have a highlighted region, then PC mode will make the content of the region the default for the string to be replaced. Moreover, PC mode will move the point to the beginning of the active region. That way, the first occurrence to be replaced will be the active region.

It is quite common for the replacement string to be similar to the string that is to be replaced. Therefore, the string that is to be replaced is a good default for the replacement string. However, PC mode does not fill in a default for the replacement string. The reason for that is the fact that the string to be replaced is always available as the previous history item via M-p.

If you do a query-replace via M-% and the mark is not active, then the default for the string to be replaced is the last string that you have searched for.

Customizing PC Mode

Exchanging Point And Mark Activates Mark

If transient mark mode is on in Emacs, exchanging the point and the mark—e.g., by pressing Ctl-x Ctl-x—will activate the mark, that is, the region will become highlighted. Some people find this annoying because they often use the mark as a "quick bookmark," that is, they use Ctl-x Ctl-x to switch between two positions in the text. Therefore, by default, PC mode rebinds Ctl-x Ctl-x so that it does not change the activation state of the mark. Instead, PC mode provides the function


for toggling the activation state of the mark. To bind this function to a key, put something like

(global-set-key [?\C-c ?t] 'pc-toggle-mark-active)

in your Emacs initialization file. If, on the other hand, you do want Ctl-x Ctl-x to always activate the mark, put the line

(pc-exchanging-point-and-mark-activates-mark 1)

in your Emacs initialization file. This function can also be used interactively to toggle the behavior of Ctl-x Ctl-x, as in

M-x pc-exchanging-point-and-mark-activates-mark

Saving Region as Kill Deactivates Mark

When you have an active selection in an MS-Window-based editor and then copy that selection to the clipboard, the selection remains active. Under Emacs' transient mark mode, by contrast, saving an active region as kill (e.g., by pressing M-w), will deactivate the mark, that is, the highlighting of the region disappears. By default, PC mode emulates the Windows-style behavior. However, you can toggle that behavior between Windows-style and transient-mark-mode-style with

M-x pc-kill-ring-save-deactivates-mark

If you always want the region to be deactivated upon saving it as kill, you can put the line

(pc-kill-ring-save-deactivates-mark 1)

in your Emacs initialization file.

Different Types of Buffer Selection with Ctl-TAB

PC Mode supports three different kinds of quick buffer selection via Ctrl-TAB. The default one is inspired by MS Visual Studio 8 (VC8); it is described above in Section "Quick Buffer Selection with Ctl-TAB."

The function

changes to a mode that is inspired by older versions of MS Visual Studio like VC6. Here, typing Ctl-TAB or Shift-Ctl-TAB will tentatively switch to other buffers. Typing TAB or RET will confirm the switch, while any other key will abandon it.

Please note: The VC6-style buffer selection does not recognize the prefix argument Ctl-u for switching to another window the way the default style does.

The function

changes to a mode where typing Ctl-TAB or Shift-Ctl-TAB will dispaly the offer to switch to other buffers in the minibuffer. Typing TAB or RET will perform the switch. Any other key will abandon the buffer selection and will be processed as usual in the current buffer. As with the VC8 style, preceding the first Ctl-TAB (or Shift-Ctl-TAB, as the case may be) with a Ctl-u will cause the buffer to be selected in another window.

The function

switches back to the default mode.

Selection Color

GNU Emacs allows you to set the foreground and background color for highlighting the region when the mark is active. PC Mode gives you colors that very much resemble the colors commonly found in Windows-based editors. Another color combination that some people like is light pink on a dark red background. To obtain this, place the lines

(set-face-foreground 'region "mistyrose")
(set-face-background 'region "firebrick")

in your Emacs initialization file, after the line that enables PC Mode.
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