Editor windows operate in two modes: overwrite mode and insert mode. The mode is a property of individual editor window. That means that each opened window may be in different mode.
To switch between modes use the Edit » Insert Mode command. The state of the command item denotes the current mode - pressed (or checked) means insert mode and unpressed (unchecked) means overwrite mode. Insert mode for the current editor window is also displayed on the status bar.
By default, each opened editor window is in overwrite mode.
Influence on Editor Commands
Insert mode changes the behavior of several editor commands. Below is a list of commands whose behavior changes when insert mode is enabled:
Typing - when insert mode is on, new data does not overwrite existing. Instead, the file size is increased, part of the file lying beyond the cursor position is moved and typed data is inserted at the cursor position.
Insert File - in overwrite mode the file's content overwrites current file's content (possibly increasing file's size). In insert mode a file is inserted at the cursor position, moving remaining part forward. The file's size is always increased.
Paste - in overwrite mode the Clipboard's content overwrites current file's content (possibly increasing file's size). In insert mode Clipboard's content is inserted at the cursor position, moving remaining part forward. The file's size is always increased.
Other editor commands are not influenced by the insert mode.