users/16932: implement $UNDO_CHANGE_NO and argument to undo widget

1 files changed, 10 insertions, 1 deletions

diff --git a/Doc/Zsh/zle.yo b/Doc/Zsh/zle.yo
index d3624b1ce..8dc46ca28 100644
--- a/Doc/Zsh/zle.yo
+++ b/Doc/Zsh/zle.yo
@@ -877,6 +877,12 @@ any predisplay string should be highlighted in bold.
 Note that the effect of tt(region_highlight) is not saved and disappears
 as soon as the line is accepted.
 )
+vindex(UNDO_CHANGE_NO)
+item(tt(UNDO_CHANGE_NO) (integer))
+A number representing the state of the undo history.  The only use
+of this is passing as an argument to the tt(undo) widget in order to
+undo back to the recorded point.  Read-only.
+)
 vindex(WIDGET)
 item(tt(WIDGET) (scalar))(
 The name of the widget currently being executed; read-only.
@@ -2164,7 +2170,10 @@ command is typed.  By default it beeps.
 )
 tindex(undo)
 item(tt(undo) (^_ ^Xu ^X^U) (unbound) (unbound))(
-Incrementally undo the last text modification.
+Incrementally undo the last text modification.  When called from a
+user-defined widget, takes an optional argument indicating a previous state
+of the undo history as returned by the tt(UNDO_CHANGE_NO) variable;
+modifications are undone until that state is reached.
 )
 tindex(redo)
 item(tt(redo))(