Hello

I'm trying to obtain such behavior for my Page_Controller form:

	function changeLanguageForm()
	{
		$arrOptions = array();
		$arrCommonLocales = i18n::get_common_languages(true);
		foreach( Translatable::get_allowed_locales() as $value )
		{
			$langName = i18n::get_lang_from_locale($value);
			$arrOptions[$value] = $arrCommonLocales[$langName];
		}
		$action = new FormAction('submitLanguageChange', '', null, null);
		$fields = new FieldSet(
			new ListboxField('langs', "", $arrOptions, Translatable::get_current_locale())
		);
		$validator = new RequiredFields('langs');
		return new Form($this, 'changeLanguageForm', $fields, $action, $validator);
	}

For pure html+js this pretty simple

<select name='myfield' onchange='this.form.submit()'>
<option .... >
...
</select>
</form>

I have no idea how to do that in ss way...

The "SS way" is to always use the Form Actions to submit a form. That said there is not straightforward way to change this.

However I would just toss out a little jQuery script on your form page to bind to the onchange event for that item.

How to do that? I suppose I have to hide submit button and fire it from js, any examples?

OK I did it by jQuery:

// Standard jQuery header
;(function($) {
$(document).ready(function() {
	$("#Form_changeLanguageForm").find(":submit").css({display: "none"});// nie pokazuj szukania
	$("#Form_changeLanguageForm select").change(function(){
		$("#Form_changeLanguageForm").find(":submit").click();
		return;
	});
// Standard jQuery footer
})
})(jQuery);

And in Page_Controller init() method:

		Requirements::javascript("jsparty/jquery/jquery-packed.js");
		Requirements::javascript("themes/".SSViewer::current_theme()."/js/behaviours.js");

Works fine but in firebug console I have frustrating error:

jQuery is not defined

How to eliminate last error?

If anyone has this error "jQuery is not defined" then check the order of the included javascript files. If jQuery isn't included before other required js files then you will have problems