title: Multiple Click Controls -- Does a layer have to be added to a map before you can add a control?
body: <p>This code works fine as is, but it seems to be dependent on the layers being added to the map before the controls are added. Is that always the case or am I doing something wrong?</p>
  
  <pre><code>          var highlightCtrl = new OpenLayers.Control.SelectFeature([a,b], {
                hover: true,
                highlightOnly: true,
                renderIntent: "temporary",
                eventListeners: {                      
                    featurehighlighted: make_popup,
                    featureunhighlighted: kill_popup
                }
            });
  
            var selectControl = new OpenLayers.Control.SelectFeature([a,b,c,d], {
                clickout: true,
                toggle: false,
                multiple: false,
                hover: false
            });
  
            map.addLayer(a);
            map.addLayer(b);
            map.addLayer(c);
            map.addLayer(d);
  
            map.addControl(highlightCtrl);
            map.addControl(selectControl);
            highlightCtrl.activate();
            selectControl.activate();
  </code></pre>