driver: Hook zle-line-finish.

Compare issue #288.

zsh-syntax-highlighting.zsh

@@ -276,8 +276,19 @@ _zsh_highlight_bind_widgets()
 }
 
 if (( $zsh_highlight_use_redrawhook )); then
+  _zsh_highlight__zle-line-finish() {
+    # Reset $WIDGET since the 'main' highlighter depends on it.
+    #
+    # A nested function is required to hide zle parameters; see 
+    # "User-defined widgets" in zshall.
+    () {
+      local -h +r WIDGET=zle-line-finish
+      _zsh_highlight "$@"
+    }
+  }
   _zsh_highlight_bind_widgets(){}
   add-zle-hook-widget zle-line-pre-redraw _zsh_highlight
+  add-zle-hook-widget zle-line-finish _zsh_highlight__zle-line-finish
 fi
 
 # Load highlighters from directory.