if ( $( "btn_show_selected" ) ) {
	
	$( "btn_show_selected" ).observe( "click", function( ele ) {
		
		ele = Event.element( ele );
	
		chks = ele.up( "form" ).getInputs( "checkbox" );
		
		chked = false;
		
		for( i = 0; i < chks.length; i++ ) {
			
			if ( chks[ i ].checked ) chked = true;
			
		}
		
		if ( chked ) {
			ele.up( "form" ).submit();	
		} else {
			alert( "Please select at least one cinema." );
		}
		
	} );
	
}