2. The Organization of the Screen

Normally, the af display occupies the whole screen. When you start af, the entire screen except for the last line is devoted to the folder you are reading. This area is called the window. The last line is a special echo area or minibuffer window where prompts appear and where you can enter responses. You can subdivide the window into different windows, each of which can be used to display a different folder (see section 20. Multiple Windows). In this manual, the word "window" always refers to the subdivisions of the screen within af.

The window that the arrow cursor is in is the selected window, in which most operations take place. Most af commands implicitly apply to the messages in the selected window. The other windows display messages for reference only, unless/until you select them.

Most windows display the details of folders, showing a header line for each message in the folder. Each header line shows a brief summary of the message's details, and is treated as a pointer to the message it describes.

Each window's last line is a mode line which describes what is going on in that window. It contains text that starts like `==== Af: something'. Its purpose is to indicate what buffer is being displayed above it in the window above it, how many messages are in the buffer, whether the buffer contains unsaved changes, and so on.

2.1 Point		The place in the buffer where commands operate.
2.2 The Echo Area		Short messages appear at the bottom of the screen.
2.3 The Header Lines		How to interpret the lines in a mail buffer.
2.4 The Mode Line		Interpreting the mode line.

2.1 Point

Within a buffer displaying a folder, an arrow pointer shows the location at which commands will take effect. This location is called point. Many af commands move point through the buffer, so that you can execute commands at different places in it.

While the arrow appears to point at a message, you should think of point as between two messages; it lies before the message that it is pointing at. Sometimes people speak of "the cursor" when they mean "point", or speak of commands that move point as "cursor motion" commands.

If you are reading several folders in af, each in its own buffer, each buffer has its own point location. A buffer that is not currently displayed remembers where point is in case you display it again later.

When there are multiple windows on the screen, each window has its own point location. The arrow shows the location of point in the selected window. This also is how you can tell which window is selected. If the same buffer appears in more than one window, each window has its own position for point in that buffer.

It is possible to move point past the last message in a buffer. This is deliberate, to allow several other commands to work properly in an "Emacs-like" way. While it may seem strange at first if you are used to other mail readers, it soon becomes familiar; and it allows you to use many af features much more easily. Most commands that deal with messages will report an error if you have moved point past the last message in the buffer, just as they would if there were no messages at all.

2.2 The Echo Area

The line at the bottom of the screen (below the mode line) is the echo area. It is used to display small amounts of text for several purposes.

Echoing means displaying the characters that you type. Outside af, the operating system normally echoes all your input. Inside af things work a little differently.

Single-character commands do not echo in af, and multi-character commands echo only if you pause while typing them. As soon as you pause for more than a second in the middle of a command, af echoes all the characters of the command so far. This is to prompt you for the rest of the command. Once echoing has started, the rest of the command echoes immediately as you type it. This behaviour is designed to give confident users fast response, while giving hesitant users maximum feedback. You can change this behaviour by setting the variable echo-keystrokes (see section 21.4 Variables).

If a command cannot be executed, it may print an error message in the echo area. Error messages are accompanied by a beep.

Some commands print informative messages in the echo area. These messages look much like error messages, but they are not announced with a beep. Sometimes the message tells you what the command has done, when this is not obvious from looking at the screen. Sometimes the sole purpose of a command is to print a message giving you specific information--for example, C-x = prints a message describing the position of point in the buffer. Commands that take a long time often display messages ending in `...' while they are working, and add `done' at the end when they are finished.

The echo area is also used to display the minibuffer, a window that is used for reading arguments to commands, such as the name of a file to be read. When the minibuffer is in use, the echo area begins with a prompt string that usually ends with a colon; also, the cursor appears in that line because it is the selected window. You can always get out of the minibuffer by typing C-g (see section 7. The Minibuffer).

2.3 The Header Lines

Most of the lines in a window which displays a folder will be header lines, which present a one-line summary of a mail message. By default a header line will look something like this:

ptr tags originator subject

ptr is the pointer which indicates the position of point in the window; the ptr will be represented as `=>' only on the line that point lies before, and as blank on all other lines. The line on which the pointer is present is sometimes referred to as the current line, and the message it represents as the current message, or the message at point.

tags are the tags of the message. Normally, this will only show system tags which af sets to show information about a message's status (see section 13. Tags).

originator is the sender of the message. If the sender's real name is available in the message headers then it will be shown here, otherwise their e-mail address will be displayed.

subject is the subject of the message.

It is possible to change the layout of the header lines by setting the variable header-line-format (see section 21.4 Variables). Also, the arrow pointer can be changed by setting the variable header-line-arrow.

2.4 The Mode Line

Each window's last line is a mode line which describes what is going on in that window. When there is only one window, the mode line appears right above the echo area. The mode line starts and ends with dashes, and it contains text like `Af: something'.

Normally, the mode line looks like this:

=ch= Af: buf == count == (modes) == pos =

This gives information about the buffer being displayed in the window: the buffer's name, what modes are in use, whether the buffer has been changed, and how far down the buffer you are currently looking.

ch contains two stars `**' if the buffer has been changed (the buffer is "modified"), two plus signs `++' if the buffer contains messages whose status has changed, or `==' if the buffer has not been changed. For a read-only buffer, it is `%*' if the buffer is modified, and `%%' otherwise.

buf is the name of the window's buffer. In most cases this is the same as the name of a folder you are processing. (see section 19. Using Multiple Buffers)

count is the number of messages in the window's buffer.

The buffer displayed in the selected window (the window that the arrow cursor is in) is also af's selected buffer, the one that most commands operate on. When we speak of what some command does to "the buffer", we are talking about the currently selected buffer.

pos tells you whether there are more messages above the top of the window, or below the bottom. If your buffer is small and it is all visible in the window, pos is `All'. Otherwise, it is `Top' if you are looking at the beginning of the buffer, `Bot' if you are looking at the end of the buffer, or `nn%', where nn is the percentage of the buffer above the top of the window.

modes lists the major mode and any minor modes which are in effect in the buffer. At any time, each buffer is in one and only one of the possible major modes. The major modes available include Mail mode (for reading folders), Typeout mode (for displaying information) and Minibuffer mode (for asking the user for input). Each major mode may be supplemented by one or more minor modes, which change the mode's behaviour in some small way. (see section 3.3 Major Modes).

It is possible to change the layout of the mode line by setting the variable mode-line-format (see section 21.4 Variables).