Index: library/nx/nx.tcl
===================================================================
diff -u -rca94e89f9a531dd4c58e22f1b87c0b941689799a -r6e4c477c4fbc7e7c256d0325763546524ee1c676
--- library/nx/nx.tcl	(.../nx.tcl)	(revision ca94e89f9a531dd4c58e22f1b87c0b941689799a)
+++ library/nx/nx.tcl	(.../nx.tcl)	(revision 6e4c477c4fbc7e7c256d0325763546524ee1c676)
@@ -1398,9 +1398,14 @@
 	    foreach cmd $cmds {
 	      foreach {op def} $cmd break
 	      #$origin trace remove variable $var $op $def
-	      if {[lindex $def 0] eq $origin} {
+	      set domain [lindex $def 0]
+	      if {$domain eq $origin} {
 		set def [concat $dest [lrange $def 1 end]]
 	      }
+	      if {[::nsf::isobject $domain] && [$domain info has type ::nx::Slot]} {
+		# slot traces are handled already by the slot mechanism
+		continue
+	      }
 	      $dest trace add variable $var $op $def
 	    }
 	  }