$_images
$_images : array
Images array.
Values correspond to 'horde-tree-image-#' CSS classes in horde/themes/screen.css.
The Horde_Core_Tree_Renderer_Html class extends the Horde_Tree_Html class to provide for creation of Horde-specific URLs.
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See the enclosed file LICENSE for license information (LGPL). If you did not receive this file, see http://www.horde.org/licenses/lgpl21.