protected function formatGroupHeader($field, $value, $mode, $row)
	{
		static $lookup = array();

		if ($GLOBALS['TL_DCA'][$this->strTable]['fields'][$field]['eval']['isAssociative'] || array_is_assoc($GLOBALS['TL_DCA'][$this->strTable]['fields'][$field]['options']))
		{
			$group = $GLOBALS['TL_DCA'][$this->strTable]['fields'][$field]['options'][$value];
		}
		elseif (\is_array($GLOBALS['TL_DCA'][$this->strTable]['fields'][$field]['options_callback']))
		{
			if (!isset($lookup[$field]))
			{
				$strClass = $GLOBALS['TL_DCA'][$this->strTable]['fields'][$field]['options_callback'][0];
				$strMethod = $GLOBALS['TL_DCA'][$this->strTable]['fields'][$field]['options_callback'][1];

				$this->import($strClass);
				$lookup[$field] = $this->$strClass->$strMethod($this);
			}

			$group = $lookup[$field][$value];
		}
		else
		{
			$group = \is_array($GLOBALS['TL_DCA'][$this->strTable]['fields'][$field]['reference'][$value]) ? $GLOBALS['TL_DCA'][$this->strTable]['fields'][$field]['reference'][$value][0] : $GLOBALS['TL_DCA'][$this->strTable]['fields'][$field]['reference'][$value];
		}

		if (empty($group))
		{
			$group = \is_array($GLOBALS['TL_LANG'][$this->strTable][$value]) ? $GLOBALS['TL_LANG'][$this->strTable][$value][0] : $GLOBALS['TL_LANG'][$this->strTable][$value];
		}

		if (empty($group))
		{
			$group = $value;

			if ($GLOBALS['TL_DCA'][$this->strTable]['fields'][$field]['eval']['isBoolean'] && $value != '-')
			{
				$group = \is_array($GLOBALS['TL_DCA'][$this->strTable]['fields'][$field]['label']) ? $GLOBALS['TL_DCA'][$this->strTable]['fields'][$field]['label'][0] : $GLOBALS['TL_DCA'][$this->strTable]['fields'][$field]['label'];
			}
		}

		// Call the group callback ($group, $sortingMode, $firstOrderBy, $row, $this)
		if (\is_array($GLOBALS['TL_DCA'][$this->strTable]['list']['label']['group_callback']))
		{
			$strClass = $GLOBALS['TL_DCA'][$this->strTable]['list']['label']['group_callback'][0];
			$strMethod = $GLOBALS['TL_DCA'][$this->strTable]['list']['label']['group_callback'][1];

			$this->import($strClass);
			$group = $this->$strClass->$strMethod($group, $mode, $field, $row, $this);
		}
		elseif (\is_callable($GLOBALS['TL_DCA'][$this->strTable]['list']['label']['group_callback']))
		{
			$group = $GLOBALS['TL_DCA'][$this->strTable]['list']['label']['group_callback']($group, $mode, $field, $row, $this);
		}

		return $group;
	}
protected function formatGroupHeader($field, $value, $mode, $row)
	{
		static $lookup = array();

		if ($GLOBALS['TL_DCA'][$this->strTable]['fields'][$field]['eval']['isAssociative'] || array_is_assoc($GLOBALS['TL_DCA'][$this->strTable]['fields'][$field]['options']))
		{
			$group = $GLOBALS['TL_DCA'][$this->strTable]['fields'][$field]['options'][$value];
		}
		elseif (\is_array($GLOBALS['TL_DCA'][$this->strTable]['fields'][$field]['options_callback']))
		{
			if (!isset($lookup[$field]))
			{
				$strClass = $GLOBALS['TL_DCA'][$this->strTable]['fields'][$field]['options_callback'][0];
				$strMethod = $GLOBALS['TL_DCA'][$this->strTable]['fields'][$field]['options_callback'][1];

				$this->import($strClass);
				$lookup[$field] = $this->$strClass->$strMethod($this);
			}

			$group = $lookup[$field][$value];
		}
		else
		{
			$group = \is_array($GLOBALS['TL_DCA'][$this->strTable]['fields'][$field]['reference'][$value]) ? $GLOBALS['TL_DCA'][$this->strTable]['fields'][$field]['reference'][$value][0] : $GLOBALS['TL_DCA'][$this->strTable]['fields'][$field]['reference'][$value];
		}

		if (empty($group))
		{
			$group = \is_array($GLOBALS['TL_LANG'][$this->strTable][$value]) ? $GLOBALS['TL_LANG'][$this->strTable][$value][0] : $GLOBALS['TL_LANG'][$this->strTable][$value];
		}

		if (empty($group))
		{
			$group = $value;

			if ($GLOBALS['TL_DCA'][$this->strTable]['fields'][$field]['eval']['isBoolean'] && $value != '-')
			{
				$group = \is_array($GLOBALS['TL_DCA'][$this->strTable]['fields'][$field]['label']) ? $GLOBALS['TL_DCA'][$this->strTable]['fields'][$field]['label'][0] : $GLOBALS['TL_DCA'][$this->strTable]['fields'][$field]['label'];
			}
		}

		// Call the group callback ($group, $sortingMode, $firstOrderBy, $row, $this)
		if (\is_array($GLOBALS['TL_DCA'][$this->strTable]['list']['label']['group_callback']))
		{
			$strClass = $GLOBALS['TL_DCA'][$this->strTable]['list']['label']['group_callback'][0];
			$strMethod = $GLOBALS['TL_DCA'][$this->strTable]['list']['label']['group_callback'][1];

			$this->import($strClass);
			$group = $this->$strClass->$strMethod($group, $mode, $field, $row, $this);
		}
		elseif (\is_callable($GLOBALS['TL_DCA'][$this->strTable]['list']['label']['group_callback']))
		{
			$group = $GLOBALS['TL_DCA'][$this->strTable]['list']['label']['group_callback']($group, $mode, $field, $row, $this);
		}

		return $group;
	}
Return the formatted group header as string

@param string  $field
@param mixed   $value
@param integer $mode
@param array   $row

@return string