Add minimum-possible taginfo powered help.

css/app.css

@@ -257,3 +257,13 @@ button small {
   -moz-animation: spinnerAnim 1.5s infinite linear;
   -moz-transform-origin: 50% 50%;
 }
+
+.tag-help,
+.tag-help a {
+    text-align:center;
+    background:#CED4F0;
+    color:#fff;
+    text-decoration:none;
+    padding:0 5px;
+    display:block;
+}

js/iD/renderer/Map.js

@@ -110,12 +110,19 @@ iD.Map = function(elem) {
 
         var ways = [], areas = [], points = [];
 
+        var active_entity = null;
+        var selected_id = selection && selection[0];
+
         for (var i = 0; i < all.length; i++) {
             var a = all[i];
             if (a.type === 'way') {
                 a._line = nodeline(a);
-                if (!iD.Way.isClosed(a)) ways.push(a);
-                else areas.push(a);
+                if (!iD.Way.isClosed(a)) {
+                    ways.push(a);
+                } else {
+                    areas.push(a);
+                }
+                if (a.id === selected_id) active_entity = a;
             } else if (a._poi) {
                 points.push(a);
             }
@@ -126,8 +133,6 @@ iD.Map = function(elem) {
             strokes = stroke_g.selectAll('path.stroke').data(ways, key),
             markers = hit_g.selectAll('image.marker').data(points, key);
 
-        var selected_id = selection && selection[0];
-
         // Fills
         fills.exit().remove();
         fills.enter().append('path')
@@ -171,12 +176,8 @@ iD.Map = function(elem) {
             return 'translate(' + pt + ')';
         });
 
-        var active_entity = all.filter(function(a) {
-            return a.id === selected_id && a.type === 'way';
-        });
-
         var handles = hit_g.selectAll('circle.handle')
-            .data(active_entity.length ? graph.fetch(active_entity[0].id).nodes : []);
+            .data(active_entity ? graph.fetch(active_entity.id).nodes : []);
 
         handles.exit().remove();
         handles.enter().append('circle')

js/iD/ui/Inspector.js

@@ -44,7 +44,7 @@ iD.Inspector = function(graph) {
                 .attr('class', 'inspector');
 
             table.append('thead').append('tr').selectAll('th')
-                .data(['tag', 'value'])
+                .data(['tag', 'value', ''])
                 .enter()
                 .append('th')
                     .text(String);
@@ -76,12 +76,18 @@ iD.Inspector = function(graph) {
                         event.update(d, newtags(table));
                         draw(formtags(table));
                     });
+
+                row.append('td').attr('class', 'tag-help').append('a')
+                    .text('?')
+                    .attr('target', '_blank')
+                    .attr('href', function(d) {
+                        return 'http://taginfo.openstreetmap.org/keys/' + d.key;
+                    });
             }
 
             var data = d3.entries(d.tags).concat([{ key: '', value: ''}]);
             draw(data);
 
-
             save = d3.select(this)
                 .append('button')
                 .text('Save')