Index: openacs-4/packages/categories/tcl/category-trees-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/categories/tcl/category-trees-procs.tcl,v
diff -u -N -r1.25.4.3 -r1.25.4.4
--- openacs-4/packages/categories/tcl/category-trees-procs.tcl	3 Oct 2013 07:56:57 -0000	1.25.4.3
+++ openacs-4/packages/categories/tcl/category-trees-procs.tcl	11 Oct 2013 12:08:21 -0000	1.25.4.4
@@ -366,12 +366,12 @@
                 set stack [linsert $stack 0 [list $right_ind $invalid_p]]
             } else {
                 incr right_ind 1
-                while {$right_ind == [lindex [lindex $stack 0] 0] && $cur_level > 0} {
+                while {$right_ind == [lindex $stack 0 0] && $cur_level > 0} {
                     incr cur_level -1
                     incr right_ind 1
                     set stack [lrange $stack 1 end]
                 }
-                set invalid_p [lindex [lindex $stack 0] 1]
+                set invalid_p [lindex $stack 0 1]
             }
         }
         if {$tree_id_old != 0} {
@@ -397,12 +397,12 @@
                 set stack [linsert $stack 0 [list $right_ind $invalid_p]]
             } else {
                 incr right_ind 1
-                while {$right_ind == [lindex [lindex $stack 0] 0] && $cur_level > 0} {
+                while {$right_ind == [lindex $stack 0 0] && $cur_level > 0} {
                     incr cur_level -1
                     incr right_ind 1
                     set stack [lrange $stack 1 end]
                 }
-                set invalid_p [lindex [lindex $stack 0] 1]
+                set invalid_p [lindex $stack 0 1]
             }
         }
         if {[info exists category_id]} {