$style
From Scriptwiki
Used to add a style (checked, disabled or both) to a menu item.
$style(N)
N = 1 for checked, N = 2 for disabled, and N = 3 for both.
The $style(N) identifier must be the first word in the menu definition.
Example
menu status { $iif($server == $null,$style(2)) Server Info .Motd:/motd .Time:/time }
The above definition creates a submenu in your status window popup which is only enabled when you are connected to an IRC server.