Index: admin/system_presets/simple/users_u.php
===================================================================
--- admin/system_presets/simple/users_u.php	(revision 14656)
+++ admin/system_presets/simple/users_u.php	(working copy)
@@ -25,7 +25,7 @@
 	// toolbar buttons
 	$remove_buttons = Array (
 //		list of users; section: Users Management -> Users
-		'users_list' => Array (/*'new_item', 'edit', 'delete', 'approve', 'decline', 'e-mail',*/ 'export', /*'view', 'dbl-click'*/),
+		'users_list' => Array (/*'new_item', 'edit', 'delete', 'approve', 'decline', 'e-mail',*/ 'export', 'frontend_mail', /*'view', 'dbl-click'*/),
 
 //		"General" tab during user adding/editing
 //		'users_edit' => Array ('select', 'cancel', 'reset_edit', 'prev', 'next'),
Index: core/admin_templates/users/users_list.tpl
===================================================================
--- core/admin_templates/users/users_list.tpl	(revision 14656)
+++ core/admin_templates/users/users_list.tpl	(working copy)
@@ -1,12 +1,12 @@
 <inp2:m_include t="incs/header"/>
 <inp2:m_RenderElement name="combined_header" section="in-portal:user_list" grid="RegularUsers" title_preset="users_list" pagination="1" prefix="u.regular"/>
-
 <!-- ToolBar -->
 <table class="toolbar" height="30" cellspacing="0" cellpadding="0" width="100%" border="0">
 <tbody>
 	<tr>
 	  	<td>
 	  		<script type="text/javascript">
+
 	  			//do not rename - this function is used in default grid for double click!
 	  			function edit()
 	  			{
@@ -55,6 +55,22 @@
 
 				a_toolbar.AddButton( new ToolBarSeparator('sep2') );
 
+				a_toolbar.AddButton( new ToolBarButton('frontend_mail', '<inp2:m_phrase label="la_ToolTip_LoginAs" escape="1"/>',
+					function() {
+
+						if (Grids['u.regular'].GetSelected().length > 1) {
+							alert('<inp2:m_phrase label="la_error_YouMustSelectOnlyOneUser" escape="1"/>');
+						} else {
+							var user_id = Grids['u.regular'].GetSelected().shift();
+							var $url = '<inp2:m_Link t="index" index_file="../index.php" user="#USER_ID#" pass="m,u" u_event="OnLoginAs" no_amp="1"/>';
+							$url = $url.replace('#USER_ID#', user_id);
+							window.open($url, 'frontend' + user_id, '');
+						}
+					}
+				) );
+
+				a_toolbar.AddButton( new ToolBarSeparator('sep3') );
+
 				<inp2:m_if check="m_ModuleEnabled" module="In-Portal">
 					a_toolbar.AddButton(
 						new ToolBarButton(
@@ -75,7 +91,7 @@
 						}
 				) );
 
-				a_toolbar.AddButton( new ToolBarSeparator('sep3') );
+				a_toolbar.AddButton( new ToolBarSeparator('sep4') );
 
 				a_toolbar.AddButton( new ToolBarButton('view', '<inp2:m_phrase label="la_ToolTip_View" escape="1"/>', function() {
 							show_viewmenu(a_toolbar,'view');
@@ -93,6 +109,6 @@
 
 <inp2:m_RenderElement name="grid" PrefixSpecial="u.regular" IdField="PortalUserId" grid="RegularUsers"/>
 <script type="text/javascript">
-	Grids['u.regular'].SetDependantToolbarButtons( new Array('edit', 'delete', 'setprimary', 'e-mail', 'approve', 'decline') );
+	Grids['u.regular'].SetDependantToolbarButtons( new Array('edit', 'delete', 'setprimary', 'e-mail', 'approve', 'decline', 'frontend_mail') );
 </script>
 <inp2:m_include t="incs/footer"/>
\ No newline at end of file
Index: core/install/english.lang
===================================================================
--- core/install/english.lang	(revision 14656)
+++ core/install/english.lang	(working copy)
@@ -257,6 +257,7 @@
 			<PHRASE Label="la_error_unknown_category" Module="Core" Type="1">VW5rbm93biBzZWN0aW9u</PHRASE>
 			<PHRASE Label="la_error_UserBanned" Module="Core" Type="1">VXNlciBCYW5uZWQ=</PHRASE>
 			<PHRASE Label="LA_ERROR_USERNOTFOUND" Module="Core" Type="1">dXNlciBub3QgZm91bmQ=</PHRASE>
+			<PHRASE Label="la_error_YouMustSelectOnlyOneUser" Module="Core" Type="1">WW91IG11c3Qgc2VsZWN0IG9ubHkgb25lIHVzZXI=</PHRASE>
 			<PHRASE Label="la_err_bad_date_format" Module="Core" Type="1">SW5jb3JyZWN0IGRhdGUgZm9ybWF0LCBwbGVhc2UgdXNlICglcykgZXguICglcyk=</PHRASE>
 			<PHRASE Label="la_err_bad_type" Module="Core" Type="1">SW5jb3JyZWN0IGRhdGEgZm9ybWF0LCBwbGVhc2UgdXNlICVz</PHRASE>
 			<PHRASE Label="la_err_invalid_format" Module="Core" Type="1">SW52YWxpZCBGb3JtYXQ=</PHRASE>
@@ -1373,6 +1374,7 @@
 			<PHRASE Label="la_ToolTip_Home" Module="Core" Type="1">SG9tZQ==</PHRASE>
 			<PHRASE Label="la_ToolTip_Import" Module="Core" Type="1">SW1wb3J0</PHRASE>
 			<PHRASE Label="la_ToolTip_ImportLanguage" Module="Core" Type="1">SW1wb3J0IExhbmd1YWdl</PHRASE>
+			<PHRASE Label="la_ToolTip_LoginAs" Module="Core" Type="1">TG9naW4gQXM=</PHRASE>
 			<PHRASE Label="la_ToolTip_MoveDown" Module="Core" Type="1">TW92ZSBEb3du</PHRASE>
 			<PHRASE Label="la_ToolTip_MoveUp" Module="Core" Type="1">TW92ZSBVcA==</PHRASE>
 			<PHRASE Label="la_ToolTip_NewAgent" Module="Core" Type="1">TmV3IEFnZW50</PHRASE>
Index: core/units/users/users_config.php
===================================================================
--- core/units/users/users_config.php	(revision 14656)
+++ core/units/users/users_config.php	(working copy)
@@ -123,7 +123,7 @@
 
 						'users_list' => Array (
 							'prefixes' => Array ('u_List'), 'format' => "!la_title_Users!",
-							'toolbar_buttons' => Array ('new_item', 'edit', 'delete', 'setprimary', 'approve', 'decline', 'e-mail', 'export', 'view', 'dbl-click'),
+							'toolbar_buttons' => Array ('new_item', 'edit', 'delete', 'setprimary', 'approve', 'decline', 'e-mail', 'export', 'view', 'dbl-click', 'frontend_mail'),
 						),
 
 						'users_edit' => Array (
Index: core/units/users/users_event_handler.php
===================================================================
--- core/units/users/users_event_handler.php	(revision 14656)
+++ core/units/users/users_event_handler.php	(working copy)
@@ -133,6 +133,14 @@
 				return defined('DBG_RESET_ROOT') && DBG_RESET_ROOT;
 			}
 
+			if ( $event->Name == 'OnLoginAs' ) {
+
+				$admin_session =& $this->Application->recallObject('Session.admin');
+				/* @var $admin_session Session */
+
+				return $admin_session->LoggedIn();
+			}
+
 			if ( !$this->Application->isAdminUser ) {
 				$user_id = $this->Application->RecallVar('user_id');
 				$items_info = $this->Application->GetVar($event->getPrefixSpecial(true));
@@ -1761,4 +1769,30 @@
 			$event->SetRedirectParam('reset', 1);
 			$event->SetRedirectParam('pass', 'm');
 		}
+
+
+		/**
+		 * Login for front-end user when admin session is present
+		 *
+		 * @param kEvent $event
+		 * @return void
+		 * @access protected
+		 */
+		protected function OnLoginAs(&$event)
+		{
+
+			$user_helper =& $this->Application->recallObject('UserHelper');
+			/* @var $user_helper UserHelper */
+
+			$user =& $user_helper->getUserObject();
+			$user->Load( $this->Application->GetVar('user') );
+
+			if ( !$user->isLoaded() ) {
+				return ;
+			}
+
+			if ( $user_helper->checkLoginPermission() ) {
+				$user_helper->loginUserById( $user->GetID() );
+			}
+		}
 	}