For me it has to be:
12.Standardized and extended string lengths throughout mIRC to allow
the use of longer variables, channel and nick names, and other
items.
and
23.Added $reptok() and $remtok() support for N = 0 to apply to all
matching items.
and
47.Added /menubar /toolbar /switchbar /treebar [on | off] commands
and $menubar, $toolbar, $switchbar, $treebar identifiers. Also
added $compact identifier to indicate normal/compact mode.