Fixes blank hover state for Structure field, closes #1891

data/core.yaml

@@ -207,6 +207,7 @@ en:
     check:
       yes: Yes
       no: No
+    none: None
   background:
     title: Background
     description: Background settings

dist/locales/en.json

@@ -254,7 +254,8 @@
         "check": {
             "yes": "Yes",
             "no": "No"
-        }
+        },
+        "none": "None"
     },
     "background": {
         "title": "Background",

js/id/ui/preset/radio.js

@@ -1,7 +1,7 @@
 iD.ui.preset.radio = function(field) {
 
     var event = d3.dispatch('change'),
-        labels, radios;
+        labels, radios, placeholder;
 
     function radio(selection) {
         selection.classed('preset-radio', true);
@@ -12,9 +12,8 @@ iD.ui.preset.radio = function(field) {
         var buttonWrap = wrap.enter().append('div')
             .attr('class', 'preset-input-wrap toggle-list');
 
-        buttonWrap.append('span')
-            .attr('class', 'placeholder')
-            .text(field.placeholder());
+        placeholder = buttonWrap.append('span')
+            .attr('class', 'placeholder');
 
         labels = wrap.selectAll('label')
             .data(field.options || field.keys);
@@ -59,6 +58,12 @@ iD.ui.preset.radio = function(field) {
 
         labels.classed('active', checked);
         radios.property('checked', checked);
+        var selection = radios.filter(function() { return this.checked; });
+        if (selection.empty()) {
+            placeholder.text(t('inspector.none'));
+        } else {
+            placeholder.text(selection.attr('value'));
+        }
     };
 
     radio.focus = function() {