diff --git a/codepot/src/codepot/controllers/main.php b/codepot/src/codepot/controllers/main.php
index b0808abd..6eb4981a 100644
--- a/codepot/src/codepot/controllers/main.php
+++ b/codepot/src/codepot/controllers/main.php
@@ -20,6 +20,33 @@ class Main extends Controller
 		redirect ("main/signin/$xurl");
 	}
 
+	function xhr_signin ()
+	{
+		$this->load->model ('UserModel', 'users');
+
+		if($this->input->post('user_name'))
+		{
+			$user_name = $this->input->post('user_name');
+			$user_pass = $this->input->post('user_pass');
+
+			if ($this->login->authenticate ($user_name, $user_pass) === FALSE)
+			{
+				print 'error - ' . $this->login->getErrorMessage();
+			}
+			else
+			{
+				$settings = $this->users->fetchSettings ($user_name);
+				if ($settings !== FALSE) $this->login->setUserSettings ($settings);
+				print 'ok';
+			}
+		}
+		else
+		{
+			$this->login->deauthenticate ();
+			print 'ok';
+		}
+	}
+
 	function signin ($xurl = '')
 	{
 		$this->load->model ('UserModel', 'users');
diff --git a/codepot/src/codepot/language/english/common_lang.php b/codepot/src/codepot/language/english/common_lang.php
index c9e9597b..c45c88f4 100644
--- a/codepot/src/codepot/language/english/common_lang.php
+++ b/codepot/src/codepot/language/english/common_lang.php
@@ -130,6 +130,7 @@ $lang['MSG_NO_SUCH_PROJECT'] = 'No such project';
 $lang['MSG_SURE_TO_DELETE_THIS'] = "I'm sure to delete this";
 $lang['MSG_FAILED_TO_READ_FILE'] = 'Failed to read file - %s';
 $lang['MSG_NO_SUCH_FILE'] = 'No such file - %s';
+$lang['MSG_SIGNIN_FAILURE'] = 'Cannot sign in';
 
 $lang['MSG_PROJECT_MEMBERSHIP_REQUIRED'] = 'You have to be a member of the %s project to perform this task';
 $lang['MSG_FORM_INPUT_INCOMPLETE'] = 'Your input is incomplete';
diff --git a/codepot/src/codepot/language/indonesian/common_lang.php b/codepot/src/codepot/language/indonesian/common_lang.php
index fc4ce2fb..94b79561 100644
--- a/codepot/src/codepot/language/indonesian/common_lang.php
+++ b/codepot/src/codepot/language/indonesian/common_lang.php
@@ -127,6 +127,7 @@ $lang['MSG_NO_SUCH_PROJECT'] = 'No such project';
 $lang['MSG_SURE_TO_DELETE_THIS'] = "Saya yakin untuk menghapus";
 $lang['MSG_FAILED_TO_READ_FILE'] = 'Failed to read file - %s';
 $lang['MSG_NO_SUCH_FILE'] = 'No such file - %s';
+$lang['MSG_SIGNIN_FAILURE'] = 'Cannot sign in';
 
 $lang['MSG_PROJECT_MEMBERSHIP_REQUIRED'] = 'You have to be a member of the %s project to perform this task';
 $lang['MSG_FORM_INPUT_INCOMPLETE'] = 'Your input is incomplete';
diff --git a/codepot/src/codepot/language/korean/common_lang.php b/codepot/src/codepot/language/korean/common_lang.php
index 5e902cac..5a59ec8f 100644
--- a/codepot/src/codepot/language/korean/common_lang.php
+++ b/codepot/src/codepot/language/korean/common_lang.php
@@ -130,6 +130,7 @@ $lang['MSG_NO_SUCH_PROJECT'] = '프로젝트가 없습니다';
 $lang['MSG_SURE_TO_DELETE_THIS'] = '반드시 이것을 삭제하고 싶어요';
 $lang['MSG_FAILED_TO_READ_FILE'] = '파일을 읽을 수 없습니다 - %s';
 $lang['MSG_NO_SUCH_FILE'] = '파일이 없습니다 - %s';
+$lang['MSG_SIGNIN_FAILURE'] = '로그인할 수 없습니다';
 
 $lang['MSG_PROJECT_MEMBERSHIP_REQUIRED'] = '이 작업을 수행하려면 %s 프로젝트의 멤버가 되어야 합니다';
 $lang['MSG_FORM_INPUT_INCOMPLETE'] = '입력이 완전하지 않습니다';
diff --git a/codepot/src/codepot/models/dbloginmodel.php b/codepot/src/codepot/models/dbloginmodel.php
index 8d5837a6..8fd50934 100644
--- a/codepot/src/codepot/models/dbloginmodel.php
+++ b/codepot/src/codepot/models/dbloginmodel.php
@@ -36,7 +36,7 @@ class DbLoginModel extends LoginModel
 
 	function authenticate ($userid, $passwd)
 	{
-		$this->db->trans_start ();
+		$this->db->trans_begin ();
 		
 		$this->db->select ('userid,passwd,email');
 		$this->db->where ('userid', $userid);
@@ -45,27 +45,36 @@ class DbLoginModel extends LoginModel
 
 		if ($this->db->trans_status() == FALSE)
 		{
-			$this->db->trans_complete ();
+			$this->setErrorMessage ($this->db->_error_message());
+			$this->db->trans_rollback ();
 			return FALSE;
 		}
 
 		$result = $query->result ();
 		if (empty($result))
 		{
-			$this->db->trans_complete ();
+			$this->setErrorMessage ('invalid credential'); // no such user name
+			$this->db->trans_rollback ();
 			return FALSE;
 		}
 
-		$this->db->trans_complete ();
-		if ($this->db->trans_status() == FALSE) return FALSE;
+		$this->db->trans_commit();
 
 		$user = $result[0];
-		if (strlen($user->passwd) < 10) return FALSE;
+		if (strlen($user->passwd) < 10) 
+		{
+			$this->setErrorMessage ('wrongly formatted password');
+			return FALSE;
+		}
 		// the last 10 characters are the salt.
 		$hexsalt = substr ($user->passwd, -10);
 		$binsalt = pack('H*' , $hexsalt);
 
-		if (strcmp ($this->format_password_with_salt($passwd,$binsalt),$user->passwd) != 0) return FALSE;
+		if (strcmp ($this->format_password_with_salt($passwd,$binsalt),$user->passwd) != 0) 
+		{
+			$this->setErrorMessage ('invalid credential'); // invalid password
+			return FALSE;
+		}
 
 		return parent::authenticate ($userid, $user->passwd, $user->email);
 	}
@@ -80,6 +89,7 @@ class DbLoginModel extends LoginModel
 
 		if ($this->db->trans_status() === FALSE)
 		{
+			$this->setErrorMessage ($this->db->_error_message());
 			$this->db->trans_rollback ();
 			return FALSE;
 		}
@@ -98,6 +108,7 @@ class DbLoginModel extends LoginModel
 
 		if ($this->db->trans_status() == FALSE)
 		{
+			$this->setErrorMessage ($this->db->_error_message());
 			$this->db->trans_complete ();
 			return FALSE;
 		}
diff --git a/codepot/src/codepot/views/code_folder.php b/codepot/src/codepot/views/code_folder.php
index 14abecf0..bd9c08ed 100644
--- a/codepot/src/codepot/views/code_folder.php
+++ b/codepot/src/codepot/views/code_folder.php
@@ -699,7 +699,6 @@ $(function () {
 				}
 			},
 			'<?php print $this->lang->line('Cancel')?>': function () {
-				if (import_in_progress) return;
 				$('#code_folder_search').dialog('close');
 			}
 		}
diff --git a/codepot/src/codepot/views/taskbar.php b/codepot/src/codepot/views/taskbar.php
index c2976a04..f37496ab 100644
--- a/codepot/src/codepot/views/taskbar.php
+++ b/codepot/src/codepot/views/taskbar.php
@@ -39,65 +39,30 @@ function show_taskbar ($con, $login)
 
 
 		print '&nbsp;';
-		//print form_submit (
-		//	'login', 
-		//	$con->lang->line('Sign out'), 
-		//	'class="button" id="taskbar_signinout_button"'
-		//);
 		printf ('<a href="#" id="taskbar_signinout_button">%s</a>', $con->lang->line('Sign out'));
 		print form_close();
 	}
 	else
 	{
-		print form_open('main/signin', array('id' => 'taskbar_signinout_form'));
+		print '<div id="taskbar_signin_container">';
 
-		print form_fieldset();
+		print '<div id="taskbar_signin_error"></div>';
 
-		$user_name = "";
-		$user_pass = "";
+		print '<div id="taskbar_signin_form">';
 
-		print form_hidden (
-			'user_url', 
-			set_value ('user_url', current_url())
-		);
-
-		/*
-		print form_label(
-			$con->lang->line('Username'), 
-			'taskbar_user_name'
-		);
-		print '&nbsp;';
-		*/
 		print form_input (
-			'user_name', 
-			set_value ('user_name', $user_name), 
+			'user_name', set_value ('user_name', ''), 
 			"size='16' id='taskbar_user_name' placeholder={$con->lang->line('Username')}"
 		);
 
-		print '&nbsp;';
-		/*
-		print form_label (
-			$con->lang->line('Password'),
-			'taskbar_user_pass'
-		);
-		print '&nbsp;';
-		*/
 		print form_password (
-			'user_pass',
-			set_value ('user_pass', $user_pass),
+			'user_pass', set_value ('user_pass', ''),
 			"size='16' id='taskbar_user_pass' placeholder={$con->lang->line('Password')}"
 		);
+		print '</div>';
+		print '</div>';
 
-		print '&nbsp;';
-		//print form_submit (
-		//	'login', 
-		//	$con->lang->line('Sign in'), 
-		//	'class="button" id="taskbar_signinout_button"'
-		//);
 		printf ('<a href="#" id="taskbar_signinout_button">%s</a>', $con->lang->line('Sign in'));
-
-		print form_fieldset_close();
-		print form_close();
 	}
 	print '</div>'; // boxb
 
@@ -120,7 +85,7 @@ function show_taskbar ($con, $login)
 	}
 	print '</ul>';
 
-	print '</div>';
+	print '</div>'; // boxa
 
 	print '</div>';
 }
@@ -140,20 +105,106 @@ function ready_to_signinout()
 <?php endif; ?>
 }
 
+var taskbar_signin_in_progress = 0;
+
 $(function () {
+	$('#taskbar_signin_container').dialog ({
+		title: '<?php print $this->lang->line('Sign in'); ?>',
+		resizable: true,
+		autoOpen: false,
+		modal: true,
+		width: 'auto',
+		height: 'auto',
+		buttons: {
+			'<?php print $this->lang->line('OK')?>': function () {
+				if (taskbar_signin_in_progress) return;
+
+				if (!!window.FormData)
+				{
+					// FormData is supported
+					taskbar_signin_in_progress = true;
+
+					var form_data = new FormData();
+					form_data.append ('user_name', $('#taskbar_user_name').val());
+					form_data.append ('user_pass', $('#taskbar_user_pass').val());
+
+					$('#taskbar_signin_container').dialog('disable');
+					$.ajax({
+						url: codepot_merge_path('<?php print site_url() ?>', '<?php print "/main/xhr_signin"; ?>'),
+						type: 'POST',
+						data: form_data,
+						mimeType: 'multipart/form-data',
+						contentType: false,
+						processData: false,
+						cache: false,
+
+						success: function (data, textStatus, jqXHR) { 
+							taskbar_signin_in_progress = false;
+
+							$('#taskbar_signin_container').dialog('enable');
+							if (data == 'ok') 
+							{
+								$('#taskbar_signin_container').dialog('close');
+								// refresh the page to the head revision
+								$(location).attr ('href', '<?php print current_url(); ?>');
+							}
+							else
+							{
+								$('#taskbar_signin_error').text(codepot_htmlspecialchars('<?php print $this->lang->line('MSG_SIGNIN_FAILURE')?>'));
+							}
+						},
+
+						error: function (jqXHR, textStatus, errorThrown) { 
+							taskbar_signin_in_progress = false;
+							$('#taskbar_signin_container').dialog('enable');
+							var errmsg = '';
+							if (errmsg == '' && errorThrown != null) errmsg = errorThrown;
+							if (errmsg == '' && textStatus != null) errmsg = textStatus;
+							if (errmsg == '') errmsg = 'Unknown error';
+							$('#taskbar_signin_error').text(codepot_htmlspecialchars(errmsg));
+						}
+					});
+				}
+				else
+				{
+					$('#taskbar_signin_error').text('NOT SUPPORTED');
+				}
+
+			},
+			'<?php print $this->lang->line('Cancel')?>': function () {
+				if (taskbar_signin_in_progress) return;
+				$('#taskbar_signin_container').dialog('close');
+			}
+		},
+
+		beforeClose: function() { 
+			// if importing is in progress, prevent dialog closing
+			return !taskbar_signin_in_progress;
+		}
+	});
+
 	$("#taskbar_user_name").button().bind ('keyup', function(e) {
-		if (e.keyCode == 13) {
-			if (ready_to_signinout()) $("#taskbar_signinout_form").submit();
+		if (e.keyCode == 13) 
+		{
+			var buttons = $("#taskbar_signin_container").dialog("option", "buttons");
+			buttons[Object.keys(buttons)[0]](); // trigger the first button
 		}
 	});
 	$("#taskbar_user_pass").button().bind ('keyup', function(e) {
-		if (e.keyCode == 13) {
-			if (ready_to_signinout()) $("#taskbar_signinout_form").submit();
+		if (e.keyCode == 13) 
+		{
+			var buttons = $("#taskbar_signin_container").dialog("option", "buttons");
+			buttons[Object.keys(buttons)[0]](); // trigger the first button
 		}
 	});
 
 	$("#taskbar_signinout_button").button().click (function() {
+		<?php if (isset($login['id']) && $login['id'] != ''): ?>
 		if (ready_to_signinout()) $("#taskbar_signinout_form").submit();
+		<?php else: ?>
+		$('#taskbar_signin_container').dialog('open');
+		<?php endif; ?>
+		return false;
 	});
 
 	$("#taskbar_project_to_find").button().autocomplete({
diff --git a/codepot/src/css/common.css b/codepot/src/css/common.css
index 0ff294d8..0a728e66 100644
--- a/codepot/src/css/common.css
+++ b/codepot/src/css/common.css
@@ -1000,6 +1000,13 @@ textarea {
 	line-height: 1em;
 }
 
+#taskbar_signin_error {
+	color: #AA3344;
+	font-weight: bold;
+	text-align: center;
+	margin-bottom: 0.5em;
+}
+
 /* ================ login page =================== */
 
 #login_user_name {