diff --git a/code/SubsitesVirtualPage.php b/code/SubsitesVirtualPage.php
index 5d8831c..d8ca46a 100644
--- a/code/SubsitesVirtualPage.php
+++ b/code/SubsitesVirtualPage.php
@@ -22,15 +22,13 @@ class SubsitesVirtualPage extends VirtualPage {
 		
 		$subsites->push(new ArrayData(array('Title' => 'Main site', 'ID' => 0)));
 
-		$subsiteSelectionField = new DropdownField(
-			"CopyContentFromID_SubsiteID", 
-			_t('SubsitesVirtualPage.SubsiteField',"Subsite"), 
-			$subsites->map('ID', 'Title'),
-			($this->CopyContentFromID) ? $this->CopyContentFrom()->SubsiteID : Session::get('SubsiteID')
-		);
 		$fields->addFieldToTab(
 			'Root.Main',
-			$subsiteSelectionField,
+			DropdownField::create(
+				"CopyContentFromID_SubsiteID", 
+				_t('SubsitesVirtualPage.SubsiteField',"Subsite"),  
+				$subsites->map('ID', 'Title')
+			)->addExtraClass('subsitestreedropdownfield-chooser no-change-track'),
 			'CopyContentFromID'
 		);
 		
@@ -44,7 +42,7 @@ class SubsitesVirtualPage extends VirtualPage {
 		);
 		
 		if(Controller::has_curr() && Controller::curr()->getRequest()) {
-			$subsiteID = Controller::curr()->getRequest()->postVar('CopyContentFromID_SubsiteID');
+			$subsiteID = Controller::curr()->getRequest()->requestVar('CopyContentFromID_SubsiteID');
 			$pageSelectionField->setSubsiteID($subsiteID);
 		}
 		$fields->replaceField('CopyContentFromID', $pageSelectionField);
@@ -111,6 +109,10 @@ class SubsitesVirtualPage extends VirtualPage {
 
 		return $labels;
 	}
+
+	public function getCopyContentFromID_SubsiteID() {
+		return ($this->CopyContentFromID) ? (int)$this->CopyContentFrom()->SubsiteID : (int)Session::get('SubsiteID');
+	}
 	
 	public function getVirtualFields() {
 		$fields = parent::getVirtualFields();
diff --git a/javascript/SubsitesTreeDropdownField.js b/javascript/SubsitesTreeDropdownField.js
index 11365b5..3b24c34 100644
--- a/javascript/SubsitesTreeDropdownField.js
+++ b/javascript/SubsitesTreeDropdownField.js
@@ -1,24 +1,30 @@
 (function($) {
 	$.entwine('ss', function($) {
-		$('.TreeDropdownField').entwine({
-			subsiteID: function() {
-				var subsiteSel = $('#CopyContentFromID_SubsiteID select')[0];
-				if(!subsiteSel) return;
-				
-				subsiteSel.onchange = (function() {
-					this.createTreeNode(true);
-					this.ajaxGetTree((function(response) {
-						this.newTreeReady(response, true);
-						this.updateTreeLabel();
-					}).bind(this));
-				}).bind(this);
-				return subsiteSel.options[subsiteSel.selectedIndex].value;
-			},
-	
+		/**
+		 * Choose a subsite from which to select pages.
+		 * Needs to clear tree dropdowns in case selection is changed.
+		 */
+		$('.subsitestreedropdownfield-chooser').entwine({
+			onchange: function() {
+				// TODO Data binding between two fields
+				// TODO create resetField method on API instead
+				var fields = $('.SubsitesTreeDropdownField');
+				fields.setValue(null);
+				fields.setTitle(null);
+				fields.find('.tree-holder').empty();
+			}
+		});
+
+		/**
+		 * Add selected subsite from separate dropdown to the request parameters
+		 * before asking for the tree.
+		 */
+		$('.TreeDropdownField.SubsitesTreeDropdownField').entwine({
 			getRequestParams: function() {
-				var name = this.find(':input:hidden').attr('name'), obj = {};
-				obj[name + '_SubsiteID'] = parseInt(this.subsiteID());
-				return obj;
+				var name = this.find(':input[type=hidden]:first').attr('name') + '_SubsiteID',
+					source = $('[name=' + name + ']'), params = {};
+				params[name] = source.length ? source.val() : null;
+				return params;
 			}
 		});
 	});