add documentation for 'mouse' configuration item

README

@@ -38,6 +38,23 @@ Available configuration parameters:
                 This value will be updated by the program when it closes.
 'mailbox':      String giving the name of the mailbox directory to search for
                 the unread message count (if unspecified, uses "Inbox").
+'mouse':        A hash which configures the actions for the program to take
+                in response to a mouse click. The keys of this hash can be
+                'left', 'middle', or 'right'. The values of the hash can take
+                the following forms:
+                'exit' - the program will terminate
+                'reconnect' - the program will reconnect to the IMAP server
+                'cmd:COMMAND' - the command COMMAND will be executed
+                The cmd:COMMAND form can be used to execute arbitrary processes
+                in response to a mouse click. This can be used to raise a mail
+                client window, for example:
+                mouse = {
+                    'middle': 'reconnect',
+                    'right': 'exit',
+                    'left': 'cmd:"C:\\Program Files\\Microsoft Office\\'
+                        'Office12\\OUTLOOK.EXE" /recycle '
+                        '/select "outlook:Sent Items"'
+                }
 'password':     String containing the password to use to connect to the server
 'port':         String containing the port number of the IMAP SSL port on
                 the mail server.