Index: core/kernel/db/db_tag_processor.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- core/kernel/db/db_tag_processor.php	(revision 15928)
+++ core/kernel/db/db_tag_processor.php	(revision )
@@ -222,11 +222,9 @@
 		$grid = $this->getUnitConfig()->getGridByName($params['grid']);
 		$grid_config = $grid['Fields'];
 
-		$picker_helper = $this->Application->recallObject('ColumnPickerHelper');
-		/* @var $picker_helper kColumnPickerHelper */
+		$picker_helper = new kColumnPickerHelper($this->getPrefixSpecial(), $params['grid']);
+		$grid_config = $picker_helper->apply($grid_config);
 
-		$picker_helper->ApplyPicker($this->getPrefixSpecial(), $grid_config, $params['grid']);
-
 		if ( $mode == 'fields' ) {
 			return "'" . join("','", array_keys($grid_config)) . "'";
 		}
@@ -247,7 +245,7 @@
 			$block_params['sort_field'] = isset($options['sort_field']) ? $options['sort_field'] : $field;
 			$block_params['filter_field'] = isset($options['filter_field']) ? $options['filter_field'] : $field;
 
-			$w = $picker_helper->GetWidth($field);
+			$w = $picker_helper->getWidth($field);
 
 			if ( $w ) {
 				// column picker width overrides width from unit config
@@ -269,21 +267,19 @@
 
 	function PickerCRC($params)
 	{
-		/* @var $picker_helper kColumnPickerHelper */
-		$picker_helper = $this->Application->recallObject('ColumnPickerHelper');
-		$picker_helper->SetGridName($params['grid']);
-		$data = $picker_helper->LoadColumns($this->getPrefixSpecial());
-		return $data['crc'];
+		$picker_helper = new kColumnPickerHelper($this->getPrefixSpecial(), $params['grid']);
+
+		return $picker_helper->getData()->getChecksum();
 	}
 
 	function FreezerPosition($params)
 	{
-		/* @var $picker_helper kColumnPickerHelper */
-		$picker_helper = $this->Application->recallObject('ColumnPickerHelper');
-		$picker_helper->SetGridName($params['grid']);
-		$data = $picker_helper->LoadColumns($this->getPrefixSpecial());
-		$freezer_pos = array_search('__FREEZER__', $data['order']);
-		return $freezer_pos === false || in_array('__FREEZER__', $data['hidden_fields']) ? 1 : ++$freezer_pos;
+		$picker_helper = new kColumnPickerHelper($this->getPrefixSpecial(), $params['grid']);
+		$data = $picker_helper->getData();
+
+		$freezer_pos = $data->getOrder('__FREEZER__');
+
+		return $freezer_pos === false || $data->isHidden('__FREEZER__') ? 1 : ++$freezer_pos;
 	}
 
 	function GridFieldsCount($params)
Index: core/units/admin/admin_tag_processor.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- core/units/admin/admin_tag_processor.php	(revision 15928)
+++ core/units/admin/admin_tag_processor.php	(revision )
@@ -629,29 +629,33 @@
 
 		function PrintColumns($params)
 		{
-			/* @var $picker_helper kColumnPickerHelper */
-			$picker_helper = $this->Application->recallObject('ColumnPickerHelper');
-			$picker_helper->SetGridName($this->Application->GetLinkedVar('grid_name'));
+			$picker_helper = new kColumnPickerHelper(
+				$this->Application->RecallVar('main_prefix'),
+				$this->Application->GetLinkedVar('grid_name')
+			);
 
-			$main_prefix = $this->Application->RecallVar('main_prefix');
-			$cols = $picker_helper->LoadColumns($main_prefix);
+			$cols = $picker_helper->getData();
 
 			$this->Application->Phrases->AddCachedPhrase('__FREEZER__', '-------------');
 
 			$o = '';
-			if (isset($params['hidden']) && $params['hidden']) {
+			if ( isset($params['hidden']) && $params['hidden'] ) {
-				foreach ($cols['hidden_fields'] as $col) {
-					$title = $this->Application->Phrase($cols['titles'][$col]);
-					$o .= "<option value='$col'>".$title;
+				foreach ( $cols->hiddenFields as $column_name ) {
+					$title = $this->Application->Phrase($cols->getTitle($column_name));
+					$o .= "<option value='$column_name'>" . $title;
 				}
 			}
 			else {
-				foreach ($cols['order'] as $col) {
-					if (in_array($col, $cols['hidden_fields'])) continue;
-					$title = $this->Application->Phrase($cols['titles'][$col]);
-					$o .= "<option value='$col'>".$title;
+				foreach ( $cols->allFields as $column_name ) {
+					if ( $cols->isHidden($column_name) ) {
+						continue;
-				}
+					}
+
+					$title = $this->Application->Phrase($cols->getTitle($column_name));
+					$o .= "<option value='$column_name'>" . $title;
-			}
+				}
+			}
+
 			return $o;
 		}
 
Index: core/kernel/db/db_event_handler.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- core/kernel/db/db_event_handler.php	(revision 15908)
+++ core/kernel/db/db_event_handler.php	(revision )
@@ -3539,11 +3539,12 @@
 
 //			$this->Application->setContentType('text/xml');
 
-			$picker_helper = $this->Application->recallObject('ColumnPickerHelper');
-			/* @var $picker_helper kColumnPickerHelper */
+			$picker_helper = new kColumnPickerHelper(
+				$event->getPrefixSpecial(),
+				$this->Application->GetVar('grid_name')
+			);
 
-			$picker_helper->PreparePicker($event->getPrefixSpecial(), $this->Application->GetVar('grid_name'));
-			$picker_helper->SaveWidths($event->getPrefixSpecial(), $this->Application->GetVar('widths'));
+			$picker_helper->saveWidths($this->Application->GetVar('widths'));
 
 			echo 'OK';
 		}
\ No newline at end of file
Index: core/units/helpers/col_picker_helper.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- core/units/helpers/col_picker_helper.php	(revision 15908)
+++ core/units/helpers/col_picker_helper.php	(revision )
@@ -16,227 +16,227 @@
 
 class kColumnPickerHelper extends kHelper {
 
-	var $PickerData;
-	var $GridName;
-	var $UseFreezer;
+	const DEFAULT_COLUMN_WIDTH = 100;
 
 	/**
-	 * Default column width in pixels
+	 * Currently processed grid name.
 	 *
-	 * @var int
+	 * @var string
 	 */
-	var $defaultColumnWidth = 100;
+	protected $gridName = '';
 
 	/**
-	 * Columns renamed by formatter in last used grid
+	 * Data of currently processed grid.
 	 *
-	 * @var Array
+	 * @var ColumnSet
 	 */
-	var $formatterRenamed = Array ();
+	protected $pickerData;
 
-	public function __construct()
+	/**
+	 * System wide setting indicating column freezer usage.
+	 *
+	 * @var boolean
+	 */
+	protected $useFreezer = true;
+
+	/**
+	 * Columns renamed by formatter in last used grid.
+	 *
+	 * @var array
+	 */
+	var $formatterRenamed = array();
+
+	/**
+	 * Create picker instance for a specific grid.
+	 *
+	 * @param string $prefix    Unit config prefix.
+	 * @param string $grid_name Grid name.
+	 */
+	public function __construct($prefix, $grid_name)
 	{
 		parent::__construct();
 
-		$this->UseFreezer = $this->Application->ConfigValue('UseColumnFreezer');
+		$splitted = $this->Application->processPrefix($prefix);
+		$this->Init($splitted['prefix'], $splitted['special']);
+
+		$this->useFreezer = $this->Application->ConfigValue('UseColumnFreezer');
+
+		$this->gridName = $grid_name;
+		$this->pickerData = $this->loadColumns();
 	}
 
-	function LoadColumns($prefix)
+	/**
+	 * Loads picker data.
+	 *
+	 * @return ColumnSet
+	 */
+	protected function loadColumns()
 	{
 		$default_value = $this->Application->isAdmin ? ALLOW_DEFAULT_SETTINGS : false;
-		$val = $this->Application->RecallPersistentVar($this->_getVarName($prefix, 'get'), $default_value);
+		$value = $this->Application->RecallPersistentVar($this->getVarName('get'), $default_value);
 
-		if (!$val) {
-			$cols = $this->RebuildColumns($prefix);
+		if ( !$value ) {
+			$columns = $this->rebuildColumns();
 		}
 		else {
-			$cols = unserialize($val);
-			$current_cols = $this->GetColumns($prefix);
+			$default_columns = $this->getDefaultColumns();
+			$columns = new ColumnSet(unserialize($value));
 
-			if ($cols === false || $cols['crc'] != $current_cols['crc'])
-			{
-				$cols = $this->RebuildColumns($prefix, $cols);
+			if ( !$columns->same($default_columns) ) {
+				$columns = $this->rebuildColumns($columns);
 			}
 		}
-		return $cols;
-	}
 
-	function PreparePicker($prefix, $grid_name)
-	{
-		$this->SetGridName($grid_name);
-		$this->PickerData = $this->LoadColumns($prefix);
+		return $columns;
 	}
 
-	function ApplyPicker($prefix, &$fields, $grid_name)
+	/**
+	 * Merges default column set with given one.
+	 *
+	 * @param ColumnSet $current_columns Currently used column set.
+	 *
+	 * @return ColumnSet
+	 */
+	protected function rebuildColumns(ColumnSet $current_columns = null)
 	{
-		$this->PreparePicker($prefix, $grid_name);
-		uksort($fields, array($this, 'CmpElems'));
-		$this->RemoveHiddenColumns($fields);
+		if ( isset($current_columns) ) {
+			$columns = $current_columns->merge($this->getDefaultColumns(), self::DEFAULT_COLUMN_WIDTH);
-	}
+		}
-
-	function SetGridName($grid_name)
-	{
-		$this->GridName = $grid_name;
+		else {
+			$columns = $this->getDefaultColumns();
-	}
+		}
 
-	function CmpElems($a, $b)
-	{
-		// remove language prefix from field, because formatter renamed column
-		if (in_array($a, $this->formatterRenamed)) {
-			$a = preg_replace('/^l[\d]+_/', '', $a);
-		}
+		$this->storeCols($columns);
 
-		if (in_array($b, $this->formatterRenamed)) {
-			$b = preg_replace('/^l[\d]+_/', '', $b);
+		return $columns;
-		}
+	}
 
-		$a_index = array_search($a, $this->PickerData['order']);
-		$b_index = array_search($b, $this->PickerData['order']);
-
-		if ($a_index == $b_index) {
-	        return 0;
-	    }
-
-	    return ($a_index < $b_index) ? -1 : 1;
-	}
-
-	function RebuildColumns($prefix, $current=null)
+	/**
+	 * Returns column set built purely from grid definition in unit config.
+	 *
+	 * @return ColumnSet
+	 */
+	protected function getDefaultColumns()
 	{
-		// get default columns from unit config
-		$cols = $this->GetColumns($prefix);
+		$grid_columns = $this->getColumnsFromUnitConfig();
 
-		if (is_array($current)) {
-			// 1. prepare visible columns
+		// we NEED to recall dummy here to apply field changes imposed by formatters,
+		// such as replacing multilingual field titles etc.
+		$this->Application->recallObject($this->getPrefixSpecial(), null, array('skip_autoload' => 1));
 
-			// keep user column order (common columns between user and default grid)
-			$common = array_intersect($current['order'], $cols['order']);
+		$counter = 0;
+		$fields = $titles = $widths = $hidden = array();
 
-			// get new columns (found in default grid, but not found in user's grid)
-			$added = array_diff($cols['order'], $current['order']);
-
-			if (in_array('__FREEZER__', $added)) {
-				// in case if freezer was added, then make it first column
-				array_unshift($common, '__FREEZER__');
-				unset($added[array_search('__FREEZER__', $added)]);
+		foreach ( $grid_columns as $name => $options ) {
+			if ( array_key_exists('formatter_renamed', $options) && $options['formatter_renamed'] ) {
+				// remove language prefix from field, because formatter renamed column
+				$this->formatterRenamed[] = $name;
+				$name = preg_replace('/^l[\d]+_/', '', $name);
 			}
 
-			$cols['order'] = array_merge($common, $added);
+			$fields[$counter] = $name;
+			$titles[$name] = isset($options['title']) ? $options['title'] : 'column:la_fld_' . $name;
+			$widths[$name] = isset($options['width']) ? $options['width'] : self::DEFAULT_COLUMN_WIDTH;
 
-			// 2. prepare hidden columns
-			if ($added) {
-				$hidden_added = array_intersect($added, $cols['hidden_fields']);
-				$cols['hidden_fields'] = array_intersect($current['order'], $current['hidden_fields']);
-
-				// when some of new columns are hidden, then keep them hidden
-				foreach ($hidden_added as $position => $field) {
-					$cols['hidden_fields'][$position] = $field;
+			if ( isset($options['hidden']) && $options['hidden'] ) {
+				$hidden[$counter] = $name;
-				}
+			}
-			}
-			else {
-				$cols['hidden_fields'] = array_intersect($current['order'], $current['hidden_fields']);
-			}
 
-			foreach($common as $col) {
-				$cols['widths'][$col] = isset($current['widths'][$col]) ? $current['widths'][$col] : $this->defaultColumnWidth;
+			$counter++;
-			}
+		}
-			$this->SetCRC($cols);
-		}
-		$this->StoreCols($prefix, $cols);
 
-		return $cols;
+		$cols = array(
+			'order' => $fields,
+			'titles' => $titles,
+			'hidden_fields' => $hidden,
+			'widths' => $widths,
+		);
+
+		return new ColumnSet($cols);
 	}
 
-	function StoreCols($prefix, $cols)
+	/**
+	 * Returns columns as-is from unit config.
+	 *
+	 * @return array
+	 */
+	protected function getColumnsFromUnitConfig()
 	{
-		$this->Application->StorePersistentVar($this->_getVarName($prefix, 'set'), serialize($cols));
+		$grid = $this->getUnitConfig()->getGridByName($this->gridName);
+
+		if ( $this->useFreezer ) {
+			$freezer_column = array('__FREEZER__' => array('title' => '__FREEZER__'));
+
+			return array_merge_recursive($freezer_column, $grid['Fields']);
-	}
+		}
 
+		return $grid['Fields'];
+	}
+
 	/**
 	* Gets variable name in persistent session to store column positions in
 	*
-	* @param string $prefix
 	* @param string $mode
 	* @return string
 	*/
-	function _getVarName($prefix, $mode = 'get')
+	protected function getVarName($mode = 'get')
 	{
-		$view_name = $this->Application->RecallVar($prefix . '_current_view');
+		$view_name = $this->Application->RecallVar($this->Prefix . '_current_view');
 
-		$ret = $prefix . '[' . $this->GridName . ']columns_.' . $view_name;
+		$ret = $this->Prefix . '[' . $this->gridName . ']columns_.' . $view_name;
+
-		if ($mode == 'get') {
+		if ( $mode == 'get' ) {
+			// fallback to old storage system, that remember only 1 grid configuration per-unit
-			if ($this->Application->RecallPersistentVar($ret) === false) {
+			if ( $this->Application->RecallPersistentVar($ret) === false ) {
-				$ret = $prefix . '_columns_.' . $view_name;
+				$ret = $this->Prefix . '_columns_.' . $view_name;
 			}
 		}
 
 		return $ret;
 	}
 
-	function GetColumns($prefix)
+	/**
+	 * Returns picker data.
+	 *
+	 * @return ColumnSet
+	 */
+	public function getData()
 	{
-		$splited = $this->Application->processPrefix($prefix);
-		$grid = $this->Application->getUnitConfig($splited['prefix'])->getGridByName($this->GridName);
-
-		if ( $this->UseFreezer ) {
-			$freezer_column = Array ('__FREEZER__' => Array ('title' => '__FREEZER__'));
-			$conf_fields = array_merge_recursive($freezer_column, $grid['Fields']);
+		return $this->pickerData;
-		}
+	}
-		else {
-			$conf_fields = $grid['Fields'];
-		}
 
-		// we NEED to recall dummy here to apply fields changes imposed by formatters,
-		// such as replacing multilingual field titles etc.
-		$dummy = $this->Application->recallObject($prefix, null, Array ('skip_autoload' => 1));
-
-		$counter = 0;
-		$hidden = array();
-		$fields = array();
-		$titles = array();
-		$widths = array();
-		foreach ($conf_fields as $name => $options) {
-			if (array_key_exists('formatter_renamed', $options) && $options['formatter_renamed']) {
-				// remove language prefix from field, because formatter renamed column
-				$this->formatterRenamed[] = $name;
-				$name = preg_replace('/^l[\d]+_/', '', $name);
+	protected function storeCols(ColumnSet $cols)
+	{
+		$this->Application->StorePersistentVar($this->getVarName('set'), serialize($cols->toArray()));
-			}
+	}
 
-			$fields[$counter] = $name;
-			$titles[$name] = isset($options['title']) ? $options['title'] : 'column:la_fld_' . $name;
-			$widths[$name] = isset($options['width']) ? $options['width'] : $this->defaultColumnWidth; // only once per grid !
+	/**
+	 * Reorders given grid configuration based on picker data and removes hidden columns.
+	 *
+	 * @param array $grid_columns
+	 *
+	 * @return array
+	 */
+	public function apply(array $grid_columns)
+	{
+		uksort($grid_columns, array($this, 'compareColumns'));
 
-			if (isset($options['hidden']) && $options['hidden']) {
-				$hidden[$counter] = $name;
+		return $this->removeHidden($grid_columns);
-			}
+	}
 
-			$counter++;
-		}
-		$sorted_fields = $fields;
-		sort($sorted_fields);
-		$cols = array(
-			'order' => $fields,
-			'titles' => $titles,
-			'hidden_fields' => $hidden,
-			'widths' => $widths,
-		);
-		$this->SetCRC($cols);
-		return $cols;
-	}
-
-	function SetCRC(&$cols)
+	/**
+	 * Removes columns, that are hidden in picker configuration.
+	 *
+	 * @param array $grid_columns Grid columns.
+	 *
+	 * @return array
+	 */
+	protected function removeHidden(array $grid_columns)
 	{
-		$sorted_fields = $cols['order'];
-		$sorted_titles = $cols['titles'];
-		asort($sorted_fields);
-		asort($sorted_titles);
-		$cols['crc'] = crc32(implode(',', $sorted_fields).implode(',', $sorted_titles));
-	}
-
-	function RemoveHiddenColumns(&$fields)
-	{
 		$to_remove = array();
-		foreach ($fields as $name => $options) {
+
+		foreach ( $grid_columns as $name => $options ) {
-			if (array_key_exists('formatter_renamed', $options) && $options['formatter_renamed']) {
+			if ( array_key_exists('formatter_renamed', $options) && $options['formatter_renamed'] ) {
 				// remove language prefix from field, because formatter renamed column
 				$name_renamed = preg_replace('/^l[\d]+_/', '', $name);
 			}
@@ -244,58 +244,337 @@
 				$name_renamed = $name;
 			}
 
-			if (array_search($name_renamed, $this->PickerData['hidden_fields']) !== false) {
+			if ( $this->pickerData->isHidden($name_renamed) ) {
 				$to_remove[] = $name;
 			}
 		}
 
-		foreach ($to_remove as $name) {
+		foreach ( $to_remove as $name ) {
-			unset($fields[$name]);
+			unset($grid_columns[$name]);
 		}
+
+		return $grid_columns;
 	}
 
-	function SaveColumns($prefix, $picked, $hidden)
+	/**
+	 * Helper function for reordering grid columns.
+	 *
+	 * @param string $first_column
+	 * @param string $second_column
+	 *
+	 * @return integer
+	 */
+	protected function compareColumns($first_column, $second_column)
 	{
+		$first_column_order = $this->pickerData->getOrder($this->fixColumnName($first_column));
+		$second_column_order = $this->pickerData->getOrder($this->fixColumnName($second_column));
+
+		if ( $first_column_order == $second_column_order ) {
+			return 0;
+		}
+
+		return ($first_column_order < $second_column_order) ? -1 : 1;
+	}
+
+	/**
+	 * Saves changes to column widths.
+	 *
+	 * @param string $picked Visible columns.
+	 * @param string $hidden Hidden columns.
+	 *
+	 * @return void
+	 */
+	public function saveColumns($picked, $hidden)
+	{
 		$order = $picked ? explode('|', $picked) : array();
 		$hidden = $hidden ? explode('|', $hidden) : array();
 		$order = array_merge($order, $hidden);
 
-		$cols = $this->LoadColumns($prefix);
-		$cols['order'] = $order;
-		$cols['hidden_fields'] = $hidden;
+		$this->pickerData->allFields = $order;
+		$this->pickerData->hiddenFields = $hidden;
 
-		$this->SetCRC($cols);
-		$this->StoreCols($prefix, $cols);
+		$this->storeCols($this->pickerData);
 	}
 
-	function SaveWidths($prefix, $widths)
+	/**
+	 * Saves changes to column widths.
+	 *
+	 * @param array|string $widths Column width info.
+	 *
+	 * @return void
+	 */
+	public function saveWidths($widths)
 	{
-		if (!is_array($widths)) {
+		if ( !is_array($widths) ) {
 			$widths = explode(':', $widths);
 		}
 
 		$i = 0;
 		array_shift($widths); // removing first col (checkbox col) width
 
-		foreach ($this->PickerData['order'] as $ord => $field) {
+		foreach ( $this->pickerData->allFields as $field ) {
-			if ($field == '__FREEZER__') {
+			if ( $field == '__FREEZER__' ) {
 				continue;
 			}
 
-			$this->PickerData['widths'][$field] = isset($widths[$i]) ? $widths[$i] : $this->defaultColumnWidth;
+			$this->pickerData->widths[$field] = isset($widths[$i]) ? $widths[$i] : self::DEFAULT_COLUMN_WIDTH;
 			$i++;
 		}
 
-		$this->StoreCols($prefix, $this->PickerData);
+		$this->storeCols($this->pickerData);
 	}
 
-	function GetWidth($field)
+	/**
+	 * Returns width of a given column.
+	 *
+	 * @param string $column_name Column name.
+	 *
+	 * @return string
+	 */
+	public function getWidth($column_name)
 	{
-		if (in_array($field, $this->formatterRenamed)) {
+		return $this->pickerData->getWidth($this->fixColumnName($column_name));
+	}
+
+	/**
+	 * Removes language prefix from formatter renamed column.
+	 *
+	 * @param string $name Column name.
+	 *
+	 * @return string
+	 */
+	protected function fixColumnName($name)
+	{
+		if ( in_array($name, $this->formatterRenamed) ) {
 			// remove language prefix from field, because formatter renamed column
-			$field = preg_replace('/^l[\d]+_/', '', $field);
+			$column_name = preg_replace('/^l[\d]+_/', '', $name);
 		}
 
-		return isset($this->PickerData['widths'][$field]) ? $this->PickerData['widths'][$field] : false;
+		return $name;
 	}
+
+}
+
+
+class ColumnSet extends kBase
+{
+
+	/**
+	 * List of all fields (key - order, value - field name).
+	 *
+	 * @var array
+	 */
+	public $allFields;
+
+	/**
+	 * List of hidden fields (key - order, value - field name).
+	 *
+	 * @var array
+	 */
+	public $hiddenFields;
+
+	/**
+	 * List of field titles (key - field name, value - label).
+	 *
+	 * @var array
+	 */
+	public $titles;
+
+	/**
+	 * List of field widths (key - field name, value - width).
+	 *
+	 * @var array
+	 */
+	public $widths;
+
+	/**
+	 * Creates column set.
+	 *
+	 * @param array $data Data.
+	 */
+	public function __construct(array $data)
+	{
+		$this->allFields = $data['order'];
+		$this->hiddenFields = $data['hidden_fields'];
+
+		$this->titles = $data['titles'];
+		$this->widths = $data['widths'];
+	}
+
+	/**
+	 * Returns array representation of an object.
+	 *
+	 * @return array
+	 */
+	public function toArray()
+	{
+		$ret = array(
+			'order' => $this->allFields,
+			'hidden_fields' => $this->hiddenFields,
+
+			'titles' => $this->titles,
+			'widths' => $this->widths,
+		);
+
+		return $ret;
+	}
+
+	/**
+	 * Returns title for a column.
+	 *
+	 * @param string $column_name Column name.
+	 *
+	 * @return string
+	 */
+	public function getTitle($column_name)
+	{
+		return $this->titles[$column_name];
+	}
+
+	/**
+	 * Returns width of a column.
+	 *
+	 * @param string $column_name Column name.
+	 * @param mixed $default Default value.
+	 *
+	 * @return string
+	 */
+	public function getWidth($column_name, $default = false)
+	{
+		return isset($this->widths[$column_name]) ? $this->widths[$column_name] : $default;
+	}
+
+	/**
+	 * Returns order for a column.
+	 *
+	 * @param string $column_name Column name.
+	 *
+	 * @return integer|boolean
+	 */
+	public function getOrder($column_name)
+	{
+		return array_search($column_name, $this->allFields);
+	}
+
+	/**
+	 * Determines if a column is hidden.
+	 *
+	 * @param string $column_name Column name.
+	 *
+	 * @return boolean
+	 */
+	public function isHidden($column_name)
+	{
+		return array_search($column_name, $this->hiddenFields) !== false;
+	}
+
+	/**
+	 * Returns checksum for current column set.
+	 *
+	 * @return integer
+	 */
+	public function getChecksum()
+	{
+		$sorted_fields = $this->allFields;
+		$sorted_titles = $this->titles;
+		asort($sorted_fields);
+		asort($sorted_titles);
+
+		return crc32(implode(',', $sorted_fields) . implode(',', $sorted_titles));
+	}
+
+	/**
+	 * Compares 2 column sets.
+	 *
+	 * @param ColumnSet $columns Column set.
+	 *
+	 * @return boolean
+	 */
+	public function same(ColumnSet $columns)
+	{
+		return $this->getChecksum() == $columns->getChecksum();
+	}
+
+	/**
+	 * Merges current column set with given one.
+	 *
+	 * @param ColumnSet $default_columns       Column set to merge with.
+	 * @param integer   $default_width Default column width.
+	 *
+	 * @return self
+	 */
+	public function merge(ColumnSet $default_columns, $default_width)
+	{
+		// keep user column order (common columns between user's and default grid)
+		$common = array_intersect($this->allFields, $default_columns->allFields);
+
+		// get new columns (found in default grid, but not found in user's grid)
+		$added = array_diff($default_columns->allFields, $this->allFields);
+
+		// in case if freezer was added, then make it first column
+		if ( in_array('__FREEZER__', $added) ) {
+			array_unshift($common, '__FREEZER__');
+			unset($added[array_search('__FREEZER__', $added)]);
+		}
+
+		// keep added column position
+		$this->allFields = $common;
+
+		foreach ( $added as $added_column ) {
+			$this->insertAfter($added_column, $default_columns->getPrecedingColumn($added_column));
+		}
+
+		$this->titles = $default_columns->titles;
+		$this->hiddenFields = array_intersect($this->allFields, $this->hiddenFields);
+
+		// update width & hidden status for added columns
+		foreach ( $added as $added_column ) {
+			$this->widths[$added_column] = $default_columns->getWidth($added_column, $default_width);
+
+			if ( $default_columns->isHidden($added_column) ) {
+				$this->hiddenFields[$default_columns->getOrder($added_column)] = $added_column;
+			}
+		}
+
+		return $this;
+	}
+
+	/**
+	 * Inserts one column after another.
+	 *
+	 * @param string $new_column   Name of column to insert.
+	 * @param string $after_column Name of column to insert after.
+	 *
+	 * @return self
+	 */
+	public function insertAfter($new_column, $after_column)
+	{
+		$addition = array($after_column, $new_column);
+		array_splice($this->allFields, $this->getOrder($after_column), 1, $addition);
+
+		return $this;
+	}
+
+	/**
+	 * Returns preceding column.
+	 *
+	 * @param string $name Column name.
+	 *
+	 * @return string
+	 */
+	public function getPrecedingColumn($name)
+	{
+		$prev_column = reset($this->allFields);
+
+		foreach ( $this->allFields as $column ) {
+			if ( $column == $name ) {
+				return $prev_column;
+			}
+
+			$prev_column = $column;
+		}
+
+		return '';
+	}
+
 }
\ No newline at end of file
Index: core/units/helpers/csv_helper.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- core/units/helpers/csv_helper.php	(revision 15908)
+++ core/units/helpers/csv_helper.php	(revision )
@@ -71,10 +71,8 @@
 			$list->Query();
 			$list->GoFirst();
 
-			$picker_helper = $this->Application->recallObject('ColumnPickerHelper');
-			/* @var $picker_helper kColumnPickerHelper */
-
-			$picker_helper->ApplyPicker(rtrim(implode('.', $prefix_elements), '.'), $grid_config, $export_data['grid']);
+			$picker_helper = new kColumnPickerHelper(rtrim(implode('.', $prefix_elements), '.'), $export_data['grid']);
+			$grid_config = $picker_helper->apply($grid_config);
 
 			if ( $first_step ) {
 				// if UTF-16, write Unicode marker
\ No newline at end of file
Index: core/units/admin/admin_events_handler.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- core/units/admin/admin_events_handler.php	(revision 15928)
+++ core/units/admin/admin_events_handler.php	(revision )
@@ -502,17 +502,15 @@
 	 */
 	protected function OnSaveColumns(kEvent $event)
 	{
-		$picker_helper = $this->Application->recallObject('ColumnPickerHelper');
-		/* @var $picker_helper kColumnPickerHelper */
+		$picker_helper = new kColumnPickerHelper(
+			$this->Application->GetVar('main_prefix'),
+			$this->Application->GetLinkedVar('grid_name')
+		);
 
-		$picker_helper->SetGridName($this->Application->GetLinkedVar('grid_name'));
-
 		$picked = trim($this->Application->GetVar('picked_str'), '|');
 		$hidden = trim($this->Application->GetVar('hidden_str'), '|');
 
-		$main_prefix = $this->Application->GetVar('main_prefix');
-
-		$picker_helper->SaveColumns($main_prefix, $picked, $hidden);
+		$picker_helper->saveColumns($picked, $hidden);
 		$this->finalizePopup($event);
 	}
 
\ No newline at end of file