Index: library/nx/nx.tcl
===================================================================
diff -u -rf20a7f81bcae20a40c4990afd431615ca1914c51 -rb6d81c6521d1e1d58f00763f5ab30a0946cc222a
--- library/nx/nx.tcl	(.../nx.tcl)	(revision f20a7f81bcae20a40c4990afd431615ca1914c51)
+++ library/nx/nx.tcl	(.../nx.tcl)	(revision b6d81c6521d1e1d58f00763f5ab30a0946cc222a)
@@ -1294,6 +1294,12 @@
       lappend objopts $prefix=${:arg}
       lappend methodopts $prefix=${:arg}
     }
+    foreach att {convert allowempty} {
+      if {[info exists :$att]} {
+	lappend objopts $att
+	lappend methodopts $att
+      }
+    }
     if {[info exists :default]} {
       set arg ${:default}
       # deactivated for now: || [string first {$} $arg] > -1
@@ -1617,6 +1623,8 @@
     valuecmd
     valuechangedcmd
     arg
+    allowempty
+    convert
   }
 
   Attribute method __default_from_cmd {obj cmd var sub op} {