diff --git a/calendar/inc/class.uical.inc.php b/calendar/inc/class.uical.inc.php
index 190a14db31..17e8e481b1 100644
--- a/calendar/inc/class.uical.inc.php
+++ b/calendar/inc/class.uical.inc.php
@@ -390,10 +390,8 @@ class uical
 			{
 				$grants[] = $grant['grantor'];
 			}
-			if ($this->multiple)
-			{
-				$file[] = array(
-					'text' => "
+			$file[] = array(
+				'text' => "
 <script type=\"text/javascript\">
 function load_cal(url,id) {
 	selectBox = document.getElementById(id);
@@ -409,32 +407,16 @@ function load_cal(url,id) {
 }
 </script>
 ".
-					$this->accountsel->selection('owner','uical_select_owner',$this->owner,'calendar+',3,False,
-						' style="width: 85%;" title="'.lang('select a %1',lang('user')).'"','',$grants).
-						$this->html->submit_button('go','>>',"load_cal('".$GLOBALS['phpgw']->link('/index.php',array(
-							'menuaction' => $_GET['menuaction'],
-							'date' => $this->date,
-						))."','uical_select_owner'); return false;",True,' title="'.lang('Go!').'"'),
-					'no_lang' => True,
-					'link' => False
-				);
-
-			}
-			else
-			{
-				$file[] = array(
-					'text' => $this->accountsel->selection('owner','uical_select_owner',$this->owner,'calendar+',0,False,
-						' style="width: 85%;" title="'.lang('select a %1',lang('user')).'"',
-						"location=location+(location.search.length ? '&' : '?')+'owner='+this.value;",$grants).
-						$this->html->a_href($this->html->image('phpgwapi','users',lang('show the calendar of multiple users')),array(
-							'menuaction' => $_GET['menuaction'],
-							'multiple' => 1,
-							'date' => $this->date,
-						)),
-					'no_lang' => True,
-					'link' => False
-				);
-			}
+				$this->accountsel->selection('owner','uical_select_owner',$this->owner,'calendar+',$this->multiple ? 3 : 1,False,
+					' style="width: '.($this->multiple && $this->common_prefs['account_selection']=='selectbox' ? 100 : 85).'%;"'.
+					' title="'.lang('select a %1',lang('user')).'" onchange="load_cal(\''.
+					$GLOBALS['phpgw']->link('/index.php',array(
+						'menuaction' => $_GET['menuaction'],
+						'date' => $this->date,
+					)).'\',\'uical_select_owner\');"','',$grants),
+				'no_lang' => True,
+				'link' => False
+			);
 		}
 
 		// Import & Export
@@ -447,7 +429,7 @@ function load_cal(url,id) {
 .divSidebox
 {
 	width: '.($this->html->user_agent=='msie'?'180px':'auto').';
-	max-width: 180px;
+	/*max-width: 180px;*/
 }
 </style>'."\n";
 		$menu_title = $GLOBALS['phpgw_info']['apps'][$appname]['title'] . ' '. lang('Menu');
diff --git a/phpgwapi/inc/class.uiaccountsel.inc.php b/phpgwapi/inc/class.uiaccountsel.inc.php
index 72345b7f43..bfd945b56f 100644
--- a/phpgwapi/inc/class.uiaccountsel.inc.php
+++ b/phpgwapi/inc/class.uiaccountsel.inc.php
@@ -65,7 +65,7 @@
 		 *  Or a string which gets added as first Option with value=0, eg. lang('all')
 		 * @return the necessary html
 		 */
-		function selection($name,$element_id,$selected,$use='accounts',$lines=1,$not=False,$options='',$onchange='',$select=False)
+		function selection($name,$element_id,$selected,$use='accounts',$lines=0,$not=False,$options='',$onchange='',$select=False)
 		{
 			//echo "<p>uiaccountsel::selection('$name',".print_r($selected,True).",'$use',$lines,$not,'$options','$onchange',".print_r($select,True).")</p>\n";
 			if (!is_array($selected))
@@ -175,16 +175,22 @@
 				'app' => $app,
 				'use' => $use,
 				'element_id'  => $element_id,
-				'single'      => !$lines,	// single selection, closes after the first selection
+				'multiple' => $lines,	// single selection (multiple=0), closes after the first selection
 			));
 			$popup_options = 'width=600,height=400,toolbar=no,scrollbars=yes,resizable=yes';
 			$app = $GLOBALS['phpgw_info']['flags']['currentapp'];
-			$single = (int) !$lines;
-			if (!$lines && $use != 'groups' && $use != 'owngroups')
+			if ($lines <= 1 && $use != 'groups' && $use != 'owngroups')
 			{
-				$options .= ' onchange="if (this.value==\'popup\') '."window.open('$link','uiaccountsel','$popup_options');".
-					($onchange ? " else { $onchange }" : '' ).'" onclick="if (this.value==\'popup\') '."window.open('$link','uiaccountsel','$popup_options');\"";
-				$select['popup'] = lang('Search').' ...';
+				if (!$lines)
+				{
+					$options .= ' onchange="if (this.value==\'popup\') '."window.open('$link','uiaccountsel','$popup_options');".
+						($onchange ? " else { $onchange }" : '' ).'" onclick="if (this.value==\'popup\') '."window.open('$link','uiaccountsel','$popup_options');\"";
+					$select['popup'] = lang('Search').' ...';
+				}
+				elseif ($onchange)
+				{
+					$options .= ' onchange="if (this.value[0]!=\',\') { '.$onchange.' }"';
+				}
 				$need_js_popup = True;
 			}
 			elseif ($onchange)
@@ -196,19 +202,23 @@
 				$select = array($extra_label) + $select;
 			}
 			//echo "<p>html::select('$name',".print_r($selected,True).",".print_r($select,True).",True,'$options')</p>\n";
-			$html = $this->html->select($name,$selected,$select,True,$options.' id="'.$element_id.'"',$lines);
+			$html = $this->html->select($name,$selected,$select,True,$options.' id="'.$element_id.'"',$lines > 1 ? $lines : 0);
 
-			if ($lines > 1 && ($this->account_selection == 'popup' || $this->account_selection == 'primary_group'))
+			if ($lines > 0 && ($this->account_selection == 'popup' || $this->account_selection == 'primary_group'))
 			{
 				$html .= '<a href="'.$link.'" target="uiaccountsel" onclick="'."window.open(this,this.target,'$popup_options'); return false;".'">'.
-					$this->html->image('phpgwapi','users',lang('search or select accounts')).'</a>';
+					$this->html->image('phpgwapi','users',$lines > 1 ? lang('search or select accounts') : lang('search or select multiple accounts')).'</a>';
 				$need_js_popup = True;
 			}
-
+			if ($lines == 1 && $this->account_selection == 'selectbox')
+			{
+				$html .= '<a href="#" onclick="'."if (selectBox = document.getElementById('$element_id')) { selectBox.size=3; selectBox.multiple=true; } return false;".'">'.
+					$this->html->image('phpgwapi','users',lang('select multiple accounts')).'</a>';
+			}
 			if($need_js_popup && !$GLOBALS['phpgw_info']['flags']['uiaccountsel']['addOption_installed'])
 			{
 				$html .= '<script language="JavaScript">
-	function addOption(id,label,value)
+	function addOption(id,label,value,do_onchange)
 	{
 		selectBox = document.getElementById(id);
 		for (i=0; i < selectBox.length; i++) {
@@ -217,11 +227,19 @@
 				selectBox.options[i].selected = true;
 				break;
 			}
+'.//		check existing entries for an entry starting with a comma, marking a not yet finished multiple selection
+'			else if (value.slice(0,1) == "," && selectBox.options[i].value.slice(0,1) == ",") {
+				selectBox.options[i].value = value;
+				selectBox.options[i].text = "'.lang('multiple').'";
+				selectBox.options[i].title = label;
+				selectBox.options[i].selected = true;
+				break;
+			}
 		}
 		if (i >= selectBox.length) {
 			selectBox.options[selectBox.length] = new Option(label,value,false,true);
 		}
-		if (selectBox.onchange) selectBox.onchange();
+		if (selectBox.onchange && do_onchange) selectBox.onchange();
 	}
 </script>';
 				$GLOBALS['phpgw_info']['flags']['uiaccountsel']['addOption_installed'] = True;
@@ -237,7 +255,7 @@
 			$use = get_var('use',array('POST','GET'));
 			$group_id = get_var('group_id',array('POST','GET'),$GLOBALS['phpgw']->accounts->data['account_primary_group']);
 			$element_id = get_var('element_id',array('POST','GET'));
-			$single = get_var('single',array('POST','GET'));
+			$multiple = get_var('multiple',array('POST','GET'));
 
 			$query = get_var('query',array('POST','GET'));
 			$query_type = get_var('query_type',array('POST','GET'));
@@ -246,7 +264,7 @@
 			$order = get_var('order',array('POST','GET'),'account_lid');
 			$sort = get_var('sort',array('POST','GET'),'ASC');
 
-			//echo "<p>uiaccountsel::popup(): app='$app', use='$use', single='$single', group_id='$group_id', element_id='$element_id', start='$start', order='$order', sort='$sort'</p>\n";
+			//echo "<p>uiaccountsel::popup(): app='$app', use='$use', multiple='$multiple', group_id='$group_id', element_id='$element_id', start='$start', order='$order', sort='$sort'</p>\n";
 
 			$this->nextmatchs = CreateObject('phpgwapi.nextmatchs');
 
@@ -291,7 +309,7 @@
 				$GLOBALS['phpgw']->template->fp('iother','other_intro',True);
 			}
 
-			if (!$single)
+			if ($multiple >= 1)
 			{
 				if (!is_object($GLOBALS['phpgw']->js))
 				{
@@ -312,7 +330,7 @@
 				'use'        => $use,
 				'group_id'   => $group_id,
 				'element_id' => $element_id,
-				'single'     => $single,
+				'multiple'   => $multiple,
 				'query_type' => $query_type,
 				'query'      => $query,
 			);
@@ -343,8 +361,8 @@
 				$link_data['group_id'] = $group['account_id'];
 
 				$GLOBALS['phpgw']->template->set_var('onclick',"addOption('$element_id','".
-					$GLOBALS['phpgw']->common->grab_owner_name($group['account_id'])."','$group[account_id]')".
-					($single ? '; window.close()' : ''));
+					$GLOBALS['phpgw']->common->grab_owner_name($group['account_id'])."','$group[account_id]',".(int)($multiple==1).")".
+					(!$multiple ? '; window.close()' : ''));
 
 				if (!$app || in_array($group['account_id'],$app_groups))
 				{
@@ -409,8 +427,8 @@
 					'firstname'	=> $user['account_firstname'] ? $user['account_firstname'] : '&nbsp;',
 					'lastname'	=> $user['account_lastname'] ? $user['account_lastname'] : '&nbsp;',
 					'onclick'	=> "addOption('$element_id','".
-						$GLOBALS['phpgw']->common->grab_owner_name($user['account_id'])."','$user[account_id]')".
-						($single ? '; window.close()' : ''),
+						$GLOBALS['phpgw']->common->grab_owner_name($user['account_id'])."','$user[account_id]',".(int)($multiple==1).")".
+						(!$multiple ? '; window.close()' : ''),
 				));
 				$GLOBALS['phpgw']->template->fp('list','accounts_list',True);
 			}
@@ -443,9 +461,20 @@
 			$GLOBALS['phpgw']->template->set_var(array(
 				'lang_selection' => lang('selection'),
 				'lang_close' => lang('close'),
+				'close_action' => 'window.close();',
 			));
+			
+			if ($multiple >= 1)
+			{
+				$GLOBALS['phpgw']->template->set_var(array(
+					'lang_close' => lang('submit'),
+					'lang_multiple' => lang('multiple'),
+					'close_action' => "oneLineSubmit('$element_id');",
+				));
+			}
+				
 
-			if (!$single)
+			if ($multiple)
 			{
 				$GLOBALS['phpgw']->template->set_var(array(
 					'selection' => $this->html->select('selected',False,array(),True,' id="uiaccountsel_popup_selection" style="width: 100%;"',13),
diff --git a/phpgwapi/templates/default/uiaccountsel.tpl b/phpgwapi/templates/default/uiaccountsel.tpl
index 4dee41c4a7..c630f1b0a3 100644
--- a/phpgwapi/templates/default/uiaccountsel.tpl
+++ b/phpgwapi/templates/default/uiaccountsel.tpl
@@ -3,10 +3,26 @@
 <script LANGUAGE="JavaScript">
 	window.focus();
 
-	function addOption(id,label,value)
+	function addOption(id,label,value,multiple)
 	{
-		opener.addOption(id,label,value);
+		openerSelectBox = opener.document.getElementById(id);
 
+		if (multiple && openerSelectBox) {
+			select = '';
+			for(i=0; i < openerSelectBox.length; i++) {
+				with (openerSelectBox.options[i]) {
+					if (selected || openerSelectBox.selectedIndex == i) {
+						select += (value.slice(0,1)==',' ? '' : ',')+value;
+					}
+				}
+			}
+			select += (select ? ',' : '')+value;
+			opener.addOption(id,label,value,0);
+			opener.addOption(id,'{lang_multiple}',select,0);
+		}
+		else {
+			opener.addOption(id,label,value,!multiple && openerSelectBox && openerSelectBox.selectedIndex < 0);
+		}
 		selectBox = document.getElementById('uiaccountsel_popup_selection');
 		if (selectBox) {
 			for (i=0; i < selectBox.length; i++) {
@@ -44,12 +60,36 @@
 		selectBox = document.getElementById('uiaccountsel_popup_selection');
 		for (i=0; i < openerSelectBox.length; i++) {
 			with (openerSelectBox.options[i]) {
-				if (selected) {
+				if (selected && value.slice(0,1) != ',') {
 					selectBox.options[selectBox.length] =  new Option(text,value);
 				}
 			}
 		}
 	}
+	
+	function oneLineSubmit(id)
+	{
+		openerSelectBox = opener.document.getElementById(id);
+
+		if (openerSelectBox) {
+			if (openerSelectBox.selectedIndex >= 0) {
+				selected = openerSelectBox.options[openerSelectBox.selectedIndex].value;
+				if (selected.slice(0,1) == ',') selected = selected.slice(1);
+				opener.addOption(id,'{lang_multiple}',selected,1);
+			}
+			else {
+				for (i=0; i < openerSelectBox.length; i++) {
+					with (openerSelectBox.options[i]) {
+						if (selected) {
+							opener.addOption(id,text,value,1);
+							break;
+						}
+					}
+				}	
+			}
+		}
+		window.close();
+	}	
 </script>
 
 <style type="text/css">
@@ -196,7 +236,7 @@
 				</tr>
 				<tr>
 					<td align="center" colspan="2">
-						<input type="button" name="close" value="{lang_close}" onClick="window.close()">
+						<input type="button" name="close" value="{lang_close}" onClick="{close_action}">
 					</td>
 				</tr>
 			</table>