diff --git a/lib/src/constants.dart b/lib/src/constants.dart
index e91b30a92..fe02365e2 100644
--- a/lib/src/constants.dart
+++ b/lib/src/constants.dart
@@ -8,12 +8,12 @@ import 'state/grid.dart';
 
 // WARNING: Do not modify line below, except for the version string
 //          (and also add new version string to scadnano_versions_to_link).
-const String CURRENT_VERSION = "0.18.9";
+const String CURRENT_VERSION = "0.18.10";
 const String INITIAL_VERSION = "0.1.0";
 
 // scadnano versions that we deploy so that older versions can be used.
 final scadnano_older_versions_to_link = [
-  "0.18.8",
+  "0.18.9",
   "0.17.14",
   // "0.17.13",
   // "0.17.12",
diff --git a/lib/src/view/design_main_strand.dart b/lib/src/view/design_main_strand.dart
index 3f9a9fa27..7d601d759 100644
--- a/lib/src/view/design_main_strand.dart
+++ b/lib/src/view/design_main_strand.dart
@@ -1337,4 +1337,6 @@ In that case the list of allowed DNA bases to which it can attach must be specif
 such as /iSp9/).''';
 
 String tooltip_allowed_bases_textfield = '''\
-TODO''';
+For internal modifications that are attached to a base, this field specifies the bases to which 
+it can be attached. (Any symbols other than ACGTacgt are ignored in this field). For instance,
+IDT can only attach a biotin modification /iBiodT/ to a T base, so one would enter T in this field.''';
diff --git a/lib/src/view/design_main_strand_modification.dart b/lib/src/view/design_main_strand_modification.dart
index d8916cf7e..db8ddc3b6 100644
--- a/lib/src/view/design_main_strand_modification.dart
+++ b/lib/src/view/design_main_strand_modification.dart
@@ -168,7 +168,6 @@ class DesignMainStrandModificationComponent extends UiComponent2<DesignMainStran
     items[idt_text_idx] = DialogText(label: 'idt text', value: props.modification.idt_text);
     items[connector_length_idx] =
         DialogInteger(label: 'connector length', value: props.modification.connector_length);
-    // items[id_idx] = DialogText(label: 'id', value: props.modification.id);
 
     if (is_internal) {
       ModificationInternal mod = (props.modification as ModificationInternal);
@@ -200,7 +199,6 @@ class DesignMainStrandModificationComponent extends UiComponent2<DesignMainStran
     String display_text = (results[display_text_idx] as DialogText).value;
     String idt_text = (results[idt_text_idx] as DialogText).value;
     int connector_length = (results[connector_length_idx] as DialogInteger).value;
-    // String id = (results[id_idx] as DialogText).value;
 
     Modification new_mod;
     if (props.modification is Modification3Prime) {
@@ -220,21 +218,20 @@ class DesignMainStrandModificationComponent extends UiComponent2<DesignMainStran
       String allowed_bases_str = (results[allowed_bases_idx] as DialogText).value;
       var allowed_bases = null;
       if (attached_to_base) {
+        // remove all symbols other than ACGTacgt
         allowed_bases_str = allowed_bases_str.replaceAll(RegExp(r'[^(A|C|G|T|a|c|g|t)]'), '');
         allowed_bases =
             {for (int i = 0; i < allowed_bases_str.length; i++) allowed_bases_str[i].toUpperCase()}.build();
       }
       new_mod = ModificationInternal(
-        // id: props.modification.id,
         display_text: display_text,
-        idt_text: props.modification.idt_text,
+        idt_text: idt_text,
         connector_length: connector_length,
         allowed_bases: allowed_bases,
       );
     }
 
-    List<SelectableModification> selectable_mods =
-        app.state.ui_state.selectables_store.selected_modifications.toList();
+    var selectable_mods = app.state.ui_state.selectables_store.selected_modifications.toList();
     if (!selectable_mods.contains(props.selectable_modification)) {
       selectable_mods.add(props.selectable_modification);
     }