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Windows and Buffers

Windows and Buffers

When e93 opens a file for editing, it reads the contents of the file into a "buffer", and then closes the file. All editing takes place within the buffer, and changes are not written back to the file until the buffer is "Saved".

A buffer is an area of memory where text is stored while it is being edited. Buffers can contain arbitrary mounts of text, and do not place any limits on the characters they contain (ASCII %body% is allowed in a buffer). Although buffers are usually used to hold the contents of files, they are also used to hold other things, like new documents, clipboards, and the text that is used by the Find and Replace functions.

All buffers have names. These names are needed so that buffers can be referred to from Tcl scripts. The name of each buffer must be unique. Buffer names can be of arbitrary length, and can contain any character except '%body%'. A buffer opened to a file is typically named with the full path name of that file. Buffer names are case sensitive.

Buffers can have "windows" associated with them. A window can be thought of as a view onto the contents of a buffer. Windows are where most editing commands are carried out. It is important to understand that buffers do not NEED to have windows associated with them. In fact, certain buffers (like clipboards) typically are not associated with windows.

Each window on the other hand, is always associated with a buffer. Windows also have names, and each takes the name of the buffer that it is associated with.

Many of the features of a window can be changed from Tcl scripts.

Some of these are:
Foreground Color
Background Color
Font
Tab Size
Location
Width/Height

See Command Reference for detailed information on commands that modify windows.

e93 maintains the concept of an "active window". This is the window that is top-most. Most menu commands operate on the active window.

Each window has a "Status bar" which gives useful information about the buffer being edited. The status bar indicates if a buffer has been modified, how many lines of text it contains, how many characters of text it contains, and gives information about the current cursor/selection position. Also, if there is a task running in the window, the status bar will let you know.


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Last Changed January 2002