diff -rU2 -x CVS openlayers.orig//includes/behaviors/js/openlayers_behavior_drawfeatures.js openlayers//includes/behaviors/js/openlayers_behavior_drawfeatures.js
--- openlayers.orig//includes/behaviors/js/openlayers_behavior_drawfeatures.js	2010-05-21 17:35:39.000000000 +0200
+++ openlayers//includes/behaviors/js/openlayers_behavior_drawfeatures.js	2010-05-21 16:29:41.000000000 +0200
@@ -6,7 +6,4 @@
  */
 
-// Declare global variable
-openlayers_drawfeature_element = null;
-
 /**
  * Update function for features
@@ -25,5 +22,5 @@
   }
   wkt_value = WktWriter.write(features_copy.features);
-  openlayers_drawfeature_element.val(wkt_value);
+  this.val(wkt_value);
 }
 
@@ -37,5 +34,5 @@
       
     // Add control
-    openlayers_drawfeature_element = 
+    var openlayers_drawfeature_element = 
       $("#" + data.map.behaviors['openlayers_behavior_drawfeatures'].element_id);
 
@@ -50,6 +47,6 @@
     if (openlayers_drawfeature_element.text() != '') {
       var wktFormat = new OpenLayers.Format.WKT();
-      wkt = openlayers_drawfeature_element.text();
-      features = wktFormat.read(wkt);
+      var wkt = openlayers_drawfeature_element.text();
+      var features = wktFormat.read(wkt);
       for(var i in features) {
         features[i].geometry = features[i].geometry.transform(
@@ -63,7 +60,7 @@
     // registering events late, because adding data
     // would result in a reprojection loop
-    data_layer.events.register('featureadded', null, update);
-    data_layer.events.register('featureremoved', null, update);
-    data_layer.events.register('featuremodified', null, update);
+    data_layer.events.register('featureadded', openlayers_drawfeature_element, update);
+    data_layer.events.register('featureremoved', openlayers_drawfeature_element, update);
+    data_layer.events.register('featuremodified', openlayers_drawfeature_element, update);
     
     var control = new OpenLayers.Control.EditingToolbar(data_layer);
diff -rU2 -x CVS openlayers.orig//includes/behaviors/js/openlayers_behavior_popup.js openlayers//includes/behaviors/js/openlayers_behavior_popup.js
--- openlayers.orig//includes/behaviors/js/openlayers_behavior_popup.js	2010-05-21 17:35:39.000000000 +0200
+++ openlayers//includes/behaviors/js/openlayers_behavior_popup.js	2010-05-21 16:29:41.000000000 +0200
@@ -11,8 +11,28 @@
  * @return
  *  Formatted HTML
+ *
+ * @todo merge with openlayers_behavior_tooltip_popup_content ?
  */
 function openlayers_behavior_popup_popup_content(feature) {
-  return "<div class='openlayers-popup'>" + feature.attributes.name +"</div>" +
-         "<div class='openlayers-popup'>" + feature.attributes.description +"</div>";
+  if ( feature.cluster )
+  {
+    var visited = []; // to keep trac of already-visited items
+    var info = '';
+    for(var i = 0; i < feature.cluster.length; i++) {
+      var pf = feature.cluster[i]; // pseudo-feature
+      // should we use layer.name rather than drupalID here ?
+      var mapwide_id = feature.layer.drupalID+pf.drupalFID;
+      // skip duplicates
+      if ( visited[mapwide_id] ) continue;
+      visited[mapwide_id] = true;
+      info += openlayers_behavior_popup_popup_content(pf);
+    }
+    return info;
+  }
+  else
+  {
+    return "<div class='openlayers-popup'>" + feature.attributes.name + "</div>" +
+           "<div class='openlayers-popup'>" + feature.attributes.description +"</div>";
+  }
 }
 
diff -rU2 -x CVS openlayers.orig//includes/behaviors/js/openlayers_behavior_tooltip.js openlayers//includes/behaviors/js/openlayers_behavior_tooltip.js
--- openlayers.orig//includes/behaviors/js/openlayers_behavior_tooltip.js	2010-05-21 17:35:39.000000000 +0200
+++ openlayers//includes/behaviors/js/openlayers_behavior_tooltip.js	2010-05-21 16:29:41.000000000 +0200
@@ -11,8 +11,28 @@
  * @return
  *  Formatted HTML
+ *
+ * @todo merge with openlayers_behavior_popup_popup_content ?
  */
 function openlayers_behavior_tooltip_popup_content(feature) {
-  return "<div class='openlayers-popup'>" + feature.attributes.name +"</div>" +
-         "<div class='openlayers-popup'>" + feature.attributes.description +"</div>";
+  if ( feature.cluster )
+  {
+    var visited = []; // to keep trac of already-visited items
+    var info = '';
+    for(var i = 0; i < feature.cluster.length; i++) {
+      var pf = feature.cluster[i]; // pseudo-feature
+      // should we use layer.name rather than drupalID here ?
+      var mapwide_id = feature.layer.drupalID+pf.drupalFID;
+      // skip duplicates
+      if ( visited[mapwide_id] ) continue;
+      visited[mapwide_id] = true;
+      info += openlayers_behavior_popup_popup_content(pf);
+    }
+    return info;
+  }
+  else
+  {
+    return "<div class='openlayers-popup'>" + feature.attributes.name +"</div>" +
+           "<div class='openlayers-popup'>" + feature.attributes.description +"</div>";
+  }
 }
 
diff -rU2 -x CVS openlayers.orig//includes/openlayers.behaviors.inc openlayers//includes/openlayers.behaviors.inc
--- openlayers.orig//includes/openlayers.behaviors.inc	2010-05-21 17:35:39.000000000 +0200
+++ openlayers//includes/openlayers.behaviors.inc	2010-05-21 16:29:41.000000000 +0200
@@ -223,4 +223,15 @@
        ),
     ),
+    'openlayers_behavior_cluster' => array(
+       'title' => t('Cluster'),
+       'description' => t('Provides vector layer features clustering by proximity'),
+       'type' => 'layer',
+       'path' => drupal_get_path('module', 'openlayers') .'/includes/behaviors',
+       'file' => 'openlayers_behavior_cluster.inc',
+       'behavior' => array(
+         'class' => 'openlayers_behavior_cluster',
+         'parent' => 'openlayers_behavior',
+       ),
+    ),
   );
 }
diff -rU2 -x CVS openlayers.orig//js/openlayers.js openlayers//js/openlayers.js
--- openlayers.orig//js/openlayers.js	2010-05-21 17:35:39.000000000 +0200
+++ openlayers//js/openlayers.js	2010-05-21 16:29:40.000000000 +0200
@@ -246,6 +246,17 @@
           // Add attribute data
           if (feature.attributes){
+            // Attributes belong to features, not single component geometries
+            // of them. But we're creating a geometry for each component for
+            // better performance and clustering support. Let's call these
+            // "pseudofeatures".
+            //
+            // In order to identify the real feature each geometry belongs to
+            // we then add a 'fid' parameter to the "pseudofeature".
+            // NOTE: 'drupalFID' is only unique within a single layer.
+            //
             newFeature.attributes = feature.attributes;
-            newFeature.data = feature.attributes;
+            newFeature.data = feature.attributes; // what is this needed for ?
+            newFeature.drupalFID = key; 
+            //newFeature.layer = layer; 
           }
 
diff -rU2 -x CVS openlayers.orig//modules/openlayers_cck/includes/behaviors/js/openlayers_cck_vector_layer.js openlayers//modules/openlayers_cck/includes/behaviors/js/openlayers_cck_vector_layer.js
--- openlayers.orig//modules/openlayers_cck/includes/behaviors/js/openlayers_cck_vector_layer.js	2010-05-21 17:35:39.000000000 +0200
+++ openlayers//modules/openlayers_cck/includes/behaviors/js/openlayers_cck_vector_layer.js	2010-05-21 16:29:41.000000000 +0200
@@ -10,5 +10,5 @@
   var data = $(context).data('openlayers');
   if (data && data.map.behaviors['openlayers_cck_vector_layer']) {
-    features = data.map.behaviors['openlayers_cck_vector_layer'].features;
+    var features = data.map.behaviors['openlayers_cck_vector_layer'].features;
 
     // Create options and layer