Synopsis:
   on [<modes>]window [<serial#>] [-|^]<match> { <action> }

Description:
   This hook is triggered whenever output to any window matches any
   existing WINDOW hook.  Extreme care should be taken when using this hook
   to redefine messages, as an ECHO command inside it will also be hooked
   by it.

Parameters:
   $0    reference number of name of the window
   $1-   text printed to the window

See Also:
   window(4)