diff --git a/htdocs/core/lib/ajax.lib.php b/htdocs/core/lib/ajax.lib.php
index a558d97569f..856d7cdfbd1 100644
--- a/htdocs/core/lib/ajax.lib.php
+++ b/htdocs/core/lib/ajax.lib.php
@@ -386,11 +386,10 @@ function ajax_autoselect($htmlname, $addlink='')
  * @param  	int		$minLengthToAutocomplete	Minimum length of input string to start autocomplete
  * @param	int		$forcefocus					Force focus on field
  * @param	string	$widthTypeOfAutocomplete	'resolve' or 'off'
- * @param	string	$modalid					ID of modal (for avoid focus problem when select2 is in a modal dialog window)
  * @return	string								Return html string to convert a select field into a combo, or '' if feature has been disabled for some reason.
  * @see selectArrayAjax of html.form.class
  */
-function ajax_combobox($htmlname, $events=array(), $minLengthToAutocomplete=0, $forcefocus=0, $widthTypeOfAutocomplete='resolve', $modalid='dialog-confirm')
+function ajax_combobox($htmlname, $events=array(), $minLengthToAutocomplete=0, $forcefocus=0, $widthTypeOfAutocomplete='resolve')
 {
 	global $conf;
 
@@ -427,7 +426,7 @@ function ajax_combobox($htmlname, $events=array(), $minLengthToAutocomplete=0, $
 					escapeMarkup: function(markup) {
 						return markup;
 					},
-					dropdownParent: $(\'#'.$modalid.'\')
+					dropdownCssClass: \'ui-dialog\'
 				})';
 	if ($forcefocus) $msg.= '.select2(\'focus\')';
 	$msg.= ';'."\n";