16 files changed, 271 insertions, 310 deletions
diff --git a/framework/Collections/TAttributeCollection.php b/framework/Collections/TAttributeCollection.php
index c8870919..abeb3c53 100644
--- a/framework/Collections/TAttributeCollection.php
+++ b/framework/Collections/TAttributeCollection.php
@@ -54,7 +54,6 @@ class TAttributeCollection extends TMap
 	 */
 	public function __get($name)
 	{
-		$name=strtolower($name);
 		return $this->contains($name)?$this->itemAt($name):parent::__get($name);
 	}
 
@@ -68,7 +67,52 @@ class TAttributeCollection extends TMap
 	 */
 	public function __set($name,$value)
 	{
-		$this->add(strtolower($name),$value);
+		$this->add($name,$value);
+	}
+
+	/**
+	 * Returns the item with the specified key.
+	 * This overrides the parent implementation by converting the key to lower case first.
+	 * @param mixed the key
+	 * @return mixed the element at the offset, null if no element is found at the offset
+	 */
+	public function itemAt($key)
+	{
+		return parent::itemAt(strtolower($key));
+	}
+
+
+	/**
+	 * Adds an item into the map.
+	 * This overrides the parent implementation by converting the key to lower case first.
+	 * @param mixed key
+	 * @param mixed value
+	 */
+	public function add($key,$value)
+	{
+		parent::add(strtolower($key),$value);
+	}
+
+	/**
+	 * Removes an item from the map by its key.
+	 * This overrides the parent implementation by converting the key to lower case first.
+	 * @param mixed the key of the item to be removed
+	 * @return mixed the removed value, null if no such key exists.
+	 */
+	public function remove($key)
+	{
+		return parent::remove(strtolower($key));
+	}
+
+	/**
+	 * Returns whether the specified is in the map.
+	 * This overrides the parent implementation by converting the key to lower case first.
+	 * @param mixed the key
+	 * @return boolean whether the map contains an item with the specified key
+	 */
+	public function contains($key)
+	{
+		return parent::contains(strtolower($key));
 	}
 
 	/**
@@ -80,7 +124,6 @@ class TAttributeCollection extends TMap
 	 */
 	public function hasProperty($name)
 	{
-		$name=strtolower($name);
 		return $this->contains($name) || parent::hasProperty($name);
 	}
 
@@ -93,7 +136,6 @@ class TAttributeCollection extends TMap
 	 */
 	public function canGetProperty($name)
 	{
-		$name=strtolower($name);
 		return $this->contains($name) || parent::canGetProperty($name);
 	}
 
diff --git a/framework/Collections/TList.php b/framework/Collections/TList.php
index 2946053b..f2628231 100644
--- a/framework/Collections/TList.php
+++ b/framework/Collections/TList.php
@@ -29,10 +29,8 @@
  * Note, count($list) will always return 1. You should use {@link getCount()}
  * to determine the number of items in the list.
  *
- * To extend TList by doing additional operations with each added or removed item,
- * you can override {@link addedItem} and {@link removedItem}.
- * You can also override {@link canAddItem} and {@link canRemoveItem} to
- * control whether to add or remove a particular item.
+ * To extend TList by doing additional operations with each addition or removal
+ * operations, override {@link insertAt()}, and {@link removeAt()}.
  *
  * @author Qiang Xue <qiang.xue@gmail.com>
  * @version $Revision: $  $Date: $
@@ -101,17 +99,10 @@ class TList extends TComponent implements IteratorAggregate,ArrayAccess
 	/**
 	 * Appends an item at the end of the list.
 	 * @param mixed new item
-	 * @throws TInvalidOperationException If the item is not allowed to be added
 	 */
 	public function add($item)
 	{
-		if($this->canAddItem($item))
-		{
-			$this->_d[$this->_c++]=$item;
-			$this->addedItem($item);
-		}
-		else
-			throw new TInvalidOperationException('list_addition_disallowed');
+		$this->insertAt($this->_c,$item);
 	}
 
 	/**
@@ -121,26 +112,18 @@ class TList extends TComponent implements IteratorAggregate,ArrayAccess
 	 * @param integer the speicified position.
 	 * @param mixed new item
 	 * @throws TInvalidDataValueException If the index specified exceeds the bound
-	 * @throws TInvalidOperationException If the item is not allowed to be added
 	 */
-	public function insert($index,$item)
+	public function insertAt($index,$item)
 	{
-		if($this->canAddItem($item))
+		if($index===$this->_c)
+			$this->_d[$this->_c++]=$item;
+		else if($index>=0 && $index<$this->_c)
 		{
-			if($index===$this->_c)
-				$this->add($item);
-			else if($index>=0 && $index<$this->_c)
-			{
-				array_splice($this->_d,$index,0,array($item));
-				$this->_c++;
-				$this->addedItem($item);
-			}
-			else
-				throw new TInvalidDataValueException('list_index_invalid',$index);
+			array_splice($this->_d,$index,0,array($item));
+			$this->_c++;
 		}
 		else
-			throw new TInvalidOperationException('list_addition_disallowed');
-
+			throw new TInvalidDataValueException('list_index_invalid',$index);
 	}
 
 	/**
@@ -148,18 +131,12 @@ class TList extends TComponent implements IteratorAggregate,ArrayAccess
 	 * The list will first search for the item.
 	 * The first item found will be removed from the list.
 	 * @param mixed the item to be removed.
-	 * @throws TInvalidOperationException If the item cannot be removed
 	 * @throws TInvalidDataValueException If the item does not exist
 	 */
 	public function remove($item)
 	{
 		if(($index=$this->indexOf($item))>=0)
-		{
-			if($this->canRemoveItem($item))
-				$this->removeAt($index);
-			else
-				throw new TInvalidOperationException('list_item_unremovable');
-		}
+			$this->removeAt($index);
 		else
 			throw new TInvalidDataValueException('list_item_inexistent');
 	}
@@ -169,25 +146,18 @@ class TList extends TComponent implements IteratorAggregate,ArrayAccess
 	 * @param integer the index of the item to be removed.
 	 * @return mixed the removed item.
 	 * @throws TOutOfRangeException If the index specified exceeds the bound
-	 * @throws TInvalidOperationException If the item cannot be removed
 	 */
 	public function removeAt($index)
 	{
 		if(isset($this->_d[$index]))
 		{
 			$item=$this->_d[$index];
-			if($this->canRemoveItem($item))
-			{
-				if($index===$this->_c-1)
-					unset($this->_d[$index]);
-				else
-					array_splice($this->_d,$index,1);
-				$this->_c--;
-				$this->removedItem($item);
-				return $item;
-			}
+			if($index===$this->_c-1)
+				unset($this->_d[$index]);
 			else
-				throw new TInvalidOperationException('list_item_unremovable');
+				array_splice($this->_d,$index,1);
+			$this->_c--;
+			return $item;
 		}
 		else
 			throw new TInvalidDataValueException('list_index_invalid',$index);
@@ -303,11 +273,11 @@ class TList extends TComponent implements IteratorAggregate,ArrayAccess
 	public function offsetSet($offset,$item)
 	{
 		if($offset===null || $offset===$this->_c)
-			$this->add($item);
+			$this->insertAt($this->_c,$item);
 		else
 		{
 			$this->removeAt($offset);
-			$this->insert($offset,$item);
+			$this->insertAt($offset,$item);
 		}
 	}
 
@@ -321,48 +291,6 @@ class TList extends TComponent implements IteratorAggregate,ArrayAccess
 	{
 		$this->removeAt($offset);
 	}
-
-	/**
-	 * This method is invoked after an item is successfully added to the list.
-	 * You can override this method to provide customized processing of the addition.
-	 * @param mixed the newly added item
-	 */
-	protected function addedItem($item)
-	{
-	}
-
-	/**
-	 * This method is invoked after an item is successfully removed from the list.
-	 * You can override this method to provide customized processing of the removal.
-	 * @param mixed the removed item
-	 */
-	protected function removedItem($item)
-	{
-	}
-
-	/**
-	 * This method is invoked before adding an item to the list.
-	 * If it returns true, the item will be added to the list, otherwise not.
-	 * You can override this method to decide whether a specific can be added.
-	 * @param mixed item to be added
-	 * @return boolean whether the item can be added to the list
-	 */
-	protected function canAddItem($item)
-	{
-		return true;
-	}
-
-	/**
-	 * This method is invoked before removing an item from the list.
-	 * If it returns true, the item will be removed from the list, otherwise not.
-	 * You can override this method to decide whether a specific can be removed.
-	 * @param mixed item to be removed
-	 * @return boolean whether the item can be removed to the list
-	 */
-	protected function canRemoveItem($item)
-	{
-		return true;
-	}
 }
 
 
diff --git a/framework/Collections/TMap.php b/framework/Collections/TMap.php
index d5a44322..be37a46b 100644
--- a/framework/Collections/TMap.php
+++ b/framework/Collections/TMap.php
@@ -100,19 +100,12 @@ class TMap extends TComponent implements IteratorAggregate,ArrayAccess
 	 * Note, if the specified key already exists, the old value will be removed first.
 	 * @param mixed key
 	 * @param mixed value
-	 * @throws TInvalidOperationException if the item cannot be added
 	 */
 	public function add($key,$value)
 	{
-		if($this->canAddItem($key,$value))
-		{
-			if(isset($this->_d[$key]))
-				$this->remove($key);
-			$this->_d[$key]=$value;
-			$this->addedItem($key,$value);
-		}
-		else
-			throw new TInvalidOperationException('map_addition_disallowed');
+		if(isset($this->_d[$key]))
+			$this->remove($key);
+		$this->_d[$key]=$value;
 	}
 
 	/**
@@ -126,14 +119,8 @@ class TMap extends TComponent implements IteratorAggregate,ArrayAccess
 		if(isset($this->_d[$key]))
 		{
 			$value=$this->_d[$key];
-			if($this->canRemoveItem($key,$value))
-			{
-				unset($this->_d[$key]);
-				$this->removedItem($key,$value);
-				return $value;
-			}
-			else
-				throw new TInvalidOperationException('map_item_unremovable');
+			unset($this->_d[$key]);
+			return $value;
 		}
 		else
 			return null;
@@ -220,7 +207,7 @@ class TMap extends TComponent implements IteratorAggregate,ArrayAccess
 	 */
 	public function offsetGet($offset)
 	{
-		return isset($this->_d[$offset]) ? $this->_d[$offset] : null;
+		return $this->itemAt($offset);
 	}
 
 	/**
@@ -243,52 +230,6 @@ class TMap extends TComponent implements IteratorAggregate,ArrayAccess
 	{
 		$this->remove($offset);
 	}
-
-	/**
-	 * This method is invoked after an item is successfully added to the map.
-	 * You can override this method provide customized processing of the addition.
-	 * @param string key to the item
-	 * @param mixed the newly added item
-	 */
-	protected function addedItem($key,$item)
-	{
-	}
-
-	/**
-	 * This method is invoked after an item is successfully removed from the map.
-	 * You can override this method provide customized processing of the removal.
-	 * @param string key to the item
-	 * @param mixed the removed item
-	 */
-	protected function removedItem($key,$item)
-	{
-	}
-
-	/**
-	 * This method is invoked before adding an item to the map.
-	 * If it returns true, the item will be added to the map, otherwise not.
-	 * You can override this method to decide whether a specific can be added.
-	 * @param string key to the item
-	 * @param mixed item to be added
-	 * @return boolean whether the item can be added to the map
-	 */
-	protected function canAddItem($key,$item)
-	{
-		return true;
-	}
-
-	/**
-	 * This method is invoked before removing an item from the map.
-	 * If it returns true, the item will be removed from the map, otherwise not.
-	 * You can override this method to decide whether a specific can be removed.
-	 * @param string key to the item
-	 * @param mixed item to be removed
-	 * @return boolean whether the item can be removed to the map
-	 */
-	protected function canRemoveItem($key,$item)
-	{
-		return true;
-	}
 }
 
 /**
diff --git a/framework/Data/TXmlDocument.php b/framework/Data/TXmlDocument.php
index 0b37258d..bb22b254 100644
--- a/framework/Data/TXmlDocument.php
+++ b/framework/Data/TXmlDocument.php
@@ -416,36 +416,41 @@ class TXmlElementList extends TList
 		return $this->_o;
 	}
 
-	/**
-	 * Overrides the parent implementation with customized processing of the newly added item.
-	 * @param mixed the newly added item
-	 */
-	protected function addedItem($item)
-	{
-		if($item->getParent()!==null)
-			$item->getParent()->getElements()->remove($item);
-		$item->setParent($this->_o);
-	}
 
 	/**
-	 * Overrides the parent implementation with customized processing of the removed item.
-	 * @param mixed the removed item
+	 * Inserts an item at the specified position.
+	 * This overrides the parent implementation by performing additional
+	 * operations for each newly added TXmlElement object.
+	 * @param integer the speicified position.
+	 * @param mixed new item
+	 * @throws TInvalidDataTypeException if the item to be inserted is not a TXmlElement object.
 	 */
-	protected function removedItem($item)
+	public function insertAt($index,$item)
 	{
-		$item->setParent(null);
+		if($item instanceof TXmlElement)
+		{
+			parent::insertAt($index,$item);
+			if($item->getParent()!==null)
+				$item->getParent()->getElements()->remove($item);
+			$item->setParent($this->_o);
+		}
+		else
+			throw new TInvalidDataTypeException('xmlelementlist_xmlelement_required');
 	}
 
 	/**
-	 * This method is invoked before adding an item to the map.
-	 * If it returns true, the item will be added to the map, otherwise not.
-	 * You can override this method to decide whether a specific can be added.
-	 * @param mixed item to be added
-	 * @return boolean whether the item can be added to the map
+	 * Removes an item at the specified position.
+	 * This overrides the parent implementation by performing additional
+	 * cleanup work when removing a TXmlElement object.
+	 * @param integer the index of the item to be removed.
+	 * @return mixed the removed item.
 	 */
-	protected function canAddItem($item)
+	public function removeAt($index)
 	{
-		return ($item instanceof TXmlElement);
+		$item=parent::removeAt($index);
+		if($item instanceof TXmlElement)
+			$item->setParent(null);
+		return $item;
 	}
 }
 
diff --git a/framework/Exceptions/messages.txt b/framework/Exceptions/messages.txt
index 69015d48..8b739623 100644
--- a/framework/Exceptions/messages.txt
+++ b/framework/Exceptions/messages.txt
@@ -15,8 +15,6 @@ component_statements_invalid			= Component '%s' is evaluating invalid PHP statem
 propertyvalue_enumvalue_invalid			= Value '%s' is a not valid enumeration value (%s).
 
 list_index_invalid						= Index '%d' is out of range.
-list_addition_disallowed				= The new item cannot be added to the list.
-list_item_unremovable					= The item cannot be removed from the list.
 list_item_inexistent					= The item cannot be found in the list.
 list_data_not_iterable					= Data must be either an array or an object implementing Traversable interface.
 
@@ -111,9 +109,13 @@ template_eventhandler_invalid			= An invalid event handler is attached to %s's e
 xmldocument_file_read_failed			= TXmlDocument is unable to read file '%s'.
 xmldocument_file_write_failed			= TXmlDocument is unable to write file '%s'.
 
+xmlelementlist_xmlelement_required		= TXmlElementList can only accept TXmlElement objects.
+
 authorizationrule_action_invalid		= TAuthorizationRule.Action can only take 'allow' or 'deny' as the value.
 authorizationrule_verb_invalid			= TAuthorizationRule.Verb can only take 'get' or 'post' as the value.
 
+authorizationrulecollection_authorizationrule_required = TAuthorizationRuleCollection can only accept TAuthorizationRule objects.
+
 usermanager_userfile_invalid			= TUserManager.UserFile '%s' is not a valid file.
 usermanager_userfile_unchangeable		= TUserManager.UserFile cannot be modified. The user module has been initialized already.
 
@@ -141,6 +143,8 @@ control_enabletheming_unchangeable		= %s.EnableTheming cannot be modified after
 control_stylesheet_applied				= StyleSheet skin has already been applied to %s.
 control_id_nonunique					= %s.ID '%s' is not unique among all controls under the same naming container.
 
+controllist_control_required			= TControlList can only accept strings or TControl objects.
+
 webcontrol_accesskey_invalid			= %s.AccessKey '%s' is invalid. It must be a single character only.
 webcontrol_style_invalid				= %s.Style must take string value only.
 
@@ -189,4 +193,16 @@ comparevalidator_controltocompare_invalid = TCompareValidator.ControlToCompare c
 
 repeater_template_required				= TRepeater.%s requires a template instance implementing ITemplate interface.
 datalist_template_required				= TDataList.%s requires a template instance implementing ITemplate interface.
-templatecolumn_template_required		= TTemplateColumn.%s requires a template instance implementing ITemplate interface.
-\ No newline at end of file
+templatecolumn_template_required		= TTemplateColumn.%s requires a template instance implementing ITemplate interface.
+
+repeateritemcollection_repeateritem_required = TRepeaterItemCollection can only accept TRepeaterItem objects.
+
+datagriditemcollection_datagriditem_required = TDataGridItemCollection can only accept TDataGridItem objects.
+
+datagridcolumncollection_datagridcolumn_required = TDataGridColumnCollection can only accept TDataGridColumn objects.
+
+datalistitemcollection_datalistitem_required = TDataListItemCollection can only accept TDataListItem objects.
+
+tablerowcollection_tablerow_required	= TTableRowCollection can only accept TTableRow objects.
+
+tablecellcollection_tablerow_required	= TTableCellCollection can only accept TTableCell objects.
+\ No newline at end of file
diff --git a/framework/Security/TAuthorizationRule.php b/framework/Security/TAuthorizationRule.php
index 2ee6de49..81955a44 100644
--- a/framework/Security/TAuthorizationRule.php
+++ b/framework/Security/TAuthorizationRule.php
@@ -200,13 +200,19 @@ class TAuthorizationRuleCollection extends TList
 	}
 
 	/**
-	 * Ensures that only instance of TAuthorizationRule is added to the collection.
-	 * @param mixed item to be added to the collection
-	 * @return boolean whether the item can be added to the collection
-	 */
-	protected function canAddItem($item)
+	 * Inserts an item at the specified position.
+	 * This overrides the parent implementation by performing additional
+	 * operations for each newly added TAuthorizationRule object.
+	 * @param integer the speicified position.
+	 * @param mixed new item
+	 * @throws TInvalidDataTypeException if the item to be inserted is not a TAuthorizationRule object.
+	 */
+	public function insertAt($index,$item)
 	{
-		return ($item instanceof TAuthorizationRule);
+		if($item instanceof TAuthorizationRule)
+			parent::insertAt($index,$item);
+		else
+			throw new TInvalidDataTypeException('authorizationrulecollection_authorizationrule_required');
 	}
 }
 
diff --git a/framework/TComponent.php b/framework/TComponent.php
index cc5fa1b5..6641fd1a 100644
--- a/framework/TComponent.php
+++ b/framework/TComponent.php
@@ -300,12 +300,12 @@ class TComponent
 	 * getting and setting properties, e.g.,
 	 * <code>
 	 * $component->OnClick[]=array($object,'buttonClicked');
-	 * $component->OnClick->insert(0,array($object,'buttonClicked'));
+	 * $component->OnClick->insertAt(0,array($object,'buttonClicked'));
 	 * </code>
 	 * which are equivalent to the following
 	 * <code>
 	 * $component->getEventHandlers('OnClick')->add(array($object,'buttonClicked'));
-	 * $component->getEventHandlers('OnClick')->insert(0,array($object,'buttonClicked'));
+	 * $component->getEventHandlers('OnClick')->insertAt(0,array($object,'buttonClicked'));
 	 * </code>
 	 *
 	 * @param string the event name
diff --git a/framework/Web/THttpRequest.php b/framework/Web/THttpRequest.php
index 2a3a35aa..ba626d07 100644
--- a/framework/Web/THttpRequest.php
+++ b/framework/Web/THttpRequest.php
@@ -140,7 +140,7 @@ class THttpRequest extends TMap implements IModule
 				$_COOKIE=$this->stripSlashes($_COOKIE);
 		}
 
-		$this->copyfrom(array_merge($_GET,$_POST));
+		$this->copyFrom(array_merge($_GET,$_POST));
 
 		$this->_initialized=true;
 		$this->getApplication()->setRequest($this);
@@ -487,32 +487,38 @@ class THttpCookieCollection extends TList
 	}
 
 	/**
-	 * Adds the cookie if owner of this collection is of THttpResponse.
-	 * This method will be invoked whenever an item is added to the collection.
+	 * Inserts an item at the specified position.
+	 * This overrides the parent implementation by performing additional
+	 * operations for each newly added THttpCookie object.
+	 * @param integer the speicified position.
+	 * @param mixed new item
+	 * @throws TInvalidDataTypeException if the item to be inserted is not a THttpCookie object.
 	 */
-	protected function addedItem($item)
+	public function insertAt($index,$item)
 	{
-		if($this->_o instanceof THttpResponse)
-			$this->_o->addCookie($item);
+		if($item instanceof THttpCookie)
+		{
+			parent::insertAt($index,$item);
+			if($this->_o instanceof THttpResponse)
+				$this->_o->addCookie($item);
+		}
+		else
+			throw new TInvalidDataTypeException('authorizationrulecollection_authorizationrule_required');
 	}
 
 	/**
-	 * Removes the cookie if owner of this collection is of THttpResponse.
-	 * This method will be invoked whenever an item is removed from the collection.
+	 * Removes an item at the specified position.
+	 * This overrides the parent implementation by performing additional
+	 * cleanup work when removing a TCookie object.
+	 * @param integer the index of the item to be removed.
+	 * @return mixed the removed item.
 	 */
-	protected function removedItem($item)
+	public function removeAt($index)
 	{
+		$item=parent::removeAt($index);
 		if($this->_o instanceof THttpResponse)
 			$this->_o->removeCookie($item);
-	}
-
-	/**
-	 * Restricts acceptable item of this collection to THttpCookie.
-	 * This method will be invoked whenever an item is to be added into the collection.
-	 */
-	protected function canAddItem($item)
-	{
-		return ($item instanceof THttpCookie);
+		return $item;
 	}
 }
 
diff --git a/framework/Web/UI/TControl.php b/framework/Web/UI/TControl.php
index 7b9fee4e..ee1b8e11 100644
--- a/framework/Web/UI/TControl.php
+++ b/framework/Web/UI/TControl.php
@@ -1487,32 +1487,39 @@ class TControlList extends TList
 	}
 
 	/**
-	 * Overrides the parent implementation with customized processing of the newly added item.
-	 * @param mixed the newly added item
-	 */
-	protected function addedItem($item)
-	{
-		if($item instanceof TControl)
+	 * Inserts an item at the specified position.
+	 * This overrides the parent implementation by performing additional
+	 * operations for each newly added child control.
+	 * @param integer the speicified position.
+	 * @param mixed new item
+	 * @throws TInvalidDataTypeException if the item to be inserted is neither a string nor a TControl.
+	 */
+	public function insertAt($index,$item)
+	{
+		if(is_string($item))
+			parent::insertAt($index,$item);
+		else if($item instanceof TControl)
+		{
+			parent::insertAt($index,$item);
 			$this->_o->addedControl($item);
+		}
+		else
+			throw new TInvalidDataTypeException('controllist_control_required');
 	}
 
 	/**
-	 * Overrides the parent implementation with customized processing of the removed item.
-	 * @param mixed the removed item
+	 * Removes an item at the specified position.
+	 * This overrides the parent implementation by performing additional
+	 * cleanup work when removing a child control.
+	 * @param integer the index of the item to be removed.
+	 * @return mixed the removed item.
 	 */
-	protected function removedItem($item)
+	public function removeAt($index)
 	{
+		$item=parent::removeAt($index);
 		if($item instanceof TControl)
 			$this->_o->removedControl($item);
-	}
-
-	/**
-	 * Only string or instance of TControl can be added into collection.
-	 * @param mixed the item to be added
-	 */
-	protected function canAddItem($item)
-	{
-		return is_string($item) || ($item instanceof TControl);
+		return $item;
 	}
 
 	/**
diff --git a/framework/Web/UI/TTemplateControl.php b/framework/Web/UI/TTemplateControl.php
index 79ada7d4..d7f1868b 100644
--- a/framework/Web/UI/TTemplateControl.php
+++ b/framework/Web/UI/TTemplateControl.php
@@ -165,7 +165,7 @@ class TTemplateControl extends TControl implements INamingContainer
 		if(isset($this->_placeholders[$id]))
 		{
 			list($parent,$loc)=$this->_placeholders[$id];
-			$parent->getControls()->insert($loc,$content);
+			$parent->getControls()->insertAt($loc,$content);
 		}
 	}
 
diff --git a/framework/Web/UI/WebControls/TDataGrid.php b/framework/Web/UI/WebControls/TDataGrid.php
index 646ead01..0aad717d 100644
--- a/framework/Web/UI/WebControls/TDataGrid.php
+++ b/framework/Web/UI/WebControls/TDataGrid.php
@@ -1553,15 +1553,18 @@ class TDataGridItem extends TTableRow implements INamingContainer
 class TDataGridItemCollection extends TList
 {
 	/**
-	 * Returns true only when the item to be added is a {@link TDataGridItem}.
-	 * This method is invoked before adding an item to the list.
-	 * If it returns true, the item will be added to the list, otherwise not.
-	 * @param mixed item to be added
-	 * @return boolean whether the item can be added to the list
+	 * Inserts an item at the specified position.
+	 * This overrides the parent implementation by inserting only TDataGridItem.
+	 * @param integer the speicified position.
+	 * @param mixed new item
+	 * @throws TInvalidDataTypeException if the item to be inserted is not a TDataGridItem.
 	 */
-	protected function canAddItem($item)
+	public function insertAt($index,$item)
 	{
-		return ($item instanceof TDataGridItem);
+		if($item instanceof TDataGridItem)
+			parent::insertAt($index,$item);
+		else
+			throw new TInvalidDataTypeException('datagriditemcollection_datagriditem_required');
 	}
 }
 
@@ -1578,15 +1581,18 @@ class TDataGridItemCollection extends TList
 class TDataGridColumnCollection extends TList
 {
 	/**
-	 * Returns true only when the item to be added is a {@link TDataGridItem}.
-	 * This method is invoked before adding an item to the list.
-	 * If it returns true, the item will be added to the list, otherwise not.
-	 * @param mixed item to be added
-	 * @return boolean whether the item can be added to the list
+	 * Inserts an item at the specified position.
+	 * This overrides the parent implementation by inserting only TDataGridColumn.
+	 * @param integer the speicified position.
+	 * @param mixed new item
+	 * @throws TInvalidDataTypeException if the item to be inserted is not a TDataGridColumn.
 	 */
-	protected function canAddItem($item)
+	public function insertAt($index,$item)
 	{
-		return ($item instanceof TDataGridColumn);
+		if($item instanceof TDataGridColumn)
+			parent::insertAt($index,$item);
+		else
+			throw new TInvalidDataTypeException('datagridcolumncollection_datagridcolumn_required');
 	}
 }
 
diff --git a/framework/Web/UI/WebControls/TDataList.php b/framework/Web/UI/WebControls/TDataList.php
index c0d74974..47b60cd6 100644
--- a/framework/Web/UI/WebControls/TDataList.php
+++ b/framework/Web/UI/WebControls/TDataList.php
@@ -1354,15 +1354,18 @@ class TDataListItem extends TWebControl implements INamingContainer
 class TDataListItemCollection extends TList
 {
 	/**
-	 * Returns true only when the item to be added is a {@link TDataListItem}.
-	 * This method is invoked before adding an item to the list.
-	 * If it returns true, the item will be added to the list, otherwise not.
-	 * @param mixed item to be added
-	 * @return boolean whether the item can be added to the list
+	 * Inserts an item at the specified position.
+	 * This overrides the parent implementation by inserting only TDataListItem.
+	 * @param integer the speicified position.
+	 * @param mixed new item
+	 * @throws TInvalidDataTypeException if the item to be inserted is not a TDataListItem.
 	 */
-	protected function canAddItem($item)
+	public function insertAt($index,$item)
 	{
-		return ($item instanceof TDataListItem);
+		if($item instanceof TDataListItem)
+			parent::insertAt($index,$item);
+		else
+			throw new TInvalidDataTypeException('datalistitemcollection_datalistitem_required');
 	}
 }
 
diff --git a/framework/Web/UI/WebControls/TDataSourceView.php b/framework/Web/UI/WebControls/TDataSourceView.php
index ab79e74c..c20556bb 100644
--- a/framework/Web/UI/WebControls/TDataSourceView.php
+++ b/framework/Web/UI/WebControls/TDataSourceView.php
@@ -103,7 +103,7 @@ abstract class TDataSourceView extends TComponent
 	 * @param array|TMap
 	 * @return integer affected rows
 	 */
-	public function insert($values)
+	public function insertAt($values)
 	{
 		throw new TNotSupportedException('datasourceview_insert_unsupported');
 	}
diff --git a/framework/Web/UI/WebControls/TListControl.php b/framework/Web/UI/WebControls/TListControl.php
index 6faccf31..8d2959b4 100644
--- a/framework/Web/UI/WebControls/TListControl.php
+++ b/framework/Web/UI/WebControls/TListControl.php
@@ -567,33 +567,18 @@ abstract class TListControl extends TDataBoundControl
 class TListItemCollection extends TList
 {
 	/**
-	 * Appends an item to the collection.
-	 * @param TListItem the item to be appended.
-	 * @throws TInvalidDataTypeException if the item being appended is neither a string nor a TListItem
-	 */
-	public function add($item)
-	{
-		if(is_string($item))
-			parent::add(new TListItem($item));
-		else if($item instanceof TListItem)
-			parent::add($item);
-		else
-			throw new TInvalidDataTypeException('listitemcollection_item_invalid');
-	}
-
-	/**
 	 * Inserts an item into the collection.
 	 * @param integer the location where the item will be inserted.
 	 * The current item at the place and the following ones will be moved backward.
 	 * @param TListItem the item to be inserted.
 	 * @throws TInvalidDataTypeException if the item being inserted is neither a string nor TListItem
 	 */
-	public function insert($index,$item)
+	public function insertAt($index,$item)
 	{
 		if(is_string($item))
-			parent::insert($index,new TListItem($item));
+			parent::insertAt($index,new TListItem($item));
 		else if($item instanceof TListItem)
-			parent::insert($index,$item);
+			parent::insertAt($index,$item);
 		else
 			throw new TInvalidDataTypeException('listitemcollection_item_invalid');
 	}
diff --git a/framework/Web/UI/WebControls/TRepeater.php b/framework/Web/UI/WebControls/TRepeater.php
index 6aa6b461..a122f387 100644
--- a/framework/Web/UI/WebControls/TRepeater.php
+++ b/framework/Web/UI/WebControls/TRepeater.php
@@ -661,15 +661,18 @@ class TRepeaterItem extends TControl implements INamingContainer
 class TRepeaterItemCollection extends TList
 {
 	/**
-	 * Returns true only when the item to be added is a {@link TRepeaterItem}.
-	 * This method is invoked before adding an item to the list.
-	 * If it returns true, the item will be added to the list, otherwise not.
-	 * @param mixed item to be added
-	 * @return boolean whether the item can be added to the list
+	 * Inserts an item at the specified position.
+	 * This overrides the parent implementation by inserting only TRepeaterItem.
+	 * @param integer the speicified position.
+	 * @param mixed new item
+	 * @throws TInvalidDataTypeException if the item to be inserted is not a TRepeaterItem.
 	 */
-	protected function canAddItem($item)
+	public function insertAt($index,$item)
 	{
-		return ($item instanceof TRepeaterItem);
+		if($item instanceof TRepeaterItem)
+			parent::insertAt($index,$item);
+		else
+			throw new TInvalidDataTypeException('repeateritemcollection_repeateritem_required');
 	}
 }
 
diff --git a/framework/Web/UI/WebControls/TTable.php b/framework/Web/UI/WebControls/TTable.php
index dab0fb60..fb70e66c 100644
--- a/framework/Web/UI/WebControls/TTable.php
+++ b/framework/Web/UI/WebControls/TTable.php
@@ -712,32 +712,38 @@ class TTableRowCollection extends TList
 	}
 
 	/**
-	 * Only string or instance of TControl can be added into collection.
-	 * @param mixed the item to be added
+	 * Inserts an item at the specified position.
+	 * This overrides the parent implementation by performing additional
+	 * operations for each newly added table row.
+	 * @param integer the speicified position.
+	 * @param mixed new item
+	 * @throws TInvalidDataTypeException if the item to be inserted is not a TTableRow object.
 	 */
-	protected function canAddItem($item)
+	public function insertAt($index,$item)
 	{
-		return ($item instanceof TTableRow);
-	}
-
-	/**
-	 * Overrides the parent implementation with customized processing of the newly added item.
-	 * @param mixed the newly added item
-	 */
-	protected function addedItem($item)
-	{
-		if($this->_owner)
-			$this->_owner->getControls()->add($item);
+		if($item instanceof TTableRow)
+		{
+			parent::insertAt($index,$item);
+			if($this->_owner)
+				$this->_owner->getControls()->insertAt($index,$item);
+		}
+		else
+			throw new TInvalidDataTypeException('tablerowcollection_tablerow_required');
 	}
 
 	/**
-	 * Overrides the parent implementation with customized processing of the removed item.
-	 * @param mixed the removed item
+	 * Removes an item at the specified position.
+	 * This overrides the parent implementation by performing additional
+	 * cleanup work when removing a table row.
+	 * @param integer the index of the item to be removed.
+	 * @return mixed the removed item.
 	 */
-	protected function removedItem($item)
+	public function removeAt($index)
 	{
-		if($this->_owner)
+		$item=parent::removeAt($index);
+		if($item instanceof TTableRow)
 			$this->_owner->getControls()->remove($item);
+		return $item;
 	}
 }
 
@@ -768,33 +774,40 @@ class TTableCellCollection extends TList
 		$this->_owner=$owner;
 	}
 
-	/**
-	 * Only string or instance of TTableCell can be added into collection.
-	 * @param mixed the item to be added
-	 */
-	protected function canAddItem($item)
-	{
-		return ($item instanceof TTableCell);
-	}
 
 	/**
-	 * Overrides the parent implementation with customized processing of the newly added item.
-	 * @param mixed the newly added item
+	 * Inserts an item at the specified position.
+	 * This overrides the parent implementation by performing additional
+	 * operations for each newly added table cell.
+	 * @param integer the speicified position.
+	 * @param mixed new item
+	 * @throws TInvalidDataTypeException if the item to be inserted is not a TTableCell object.
 	 */
-	protected function addedItem($item)
+	public function insertAt($index,$item)
 	{
-		if($this->_owner)
-			$this->_owner->getControls()->add($item);
+		if($item instanceof TTableCell)
+		{
+			parent::insertAt($index,$item);
+			if($this->_owner)
+				$this->_owner->getControls()->insertAt($index,$item);
+		}
+		else
+			throw new TInvalidDataTypeException('tablecellcollection_tablecell_required');
 	}
 
 	/**
-	 * Overrides the parent implementation with customized processing of the removed item.
-	 * @param mixed the removed item
+	 * Removes an item at the specified position.
+	 * This overrides the parent implementation by performing additional
+	 * cleanup work when removing a table cell.
+	 * @param integer the index of the item to be removed.
+	 * @return mixed the removed item.
 	 */
-	protected function removedItem($item)
+	public function removeAt($index)
 	{
-		if($this->_owner)
+		$item=parent::removeAt($index);
+		if($item instanceof TTableCell)
 			$this->_owner->getControls()->remove($item);
+		return $item;
 	}
 }
 ?>
 \ No newline at end of file