Index: simple_grid.js
===================================================================
--- simple_grid.js	(revision 13756)
+++ simple_grid.js	(working copy)
@@ -128,13 +128,30 @@
 }
 
 SimpleGrid.prototype.removeRecord = function ($number) {
+	var $index = array_search($number, this.ItemIDs);
+
+	if ($index == -1) {
+		// don't allow to delete missing rows
+		return false;
+	}
+
 	this.getControl('container').removeChild( this.getControl($number) );
-	var $index = array_search($number, this.ItemIDs);
+
 	this.ItemIDs.splice($index, 1);
+
 	this.renumberRecords();
 	this.updateTotals();
+
+	return true;
 }
 
+SimpleGrid.prototype.removeRecords = function () {
+	while (this.ItemIDs.length > 0) {
+		var $item_id = this.ItemIDs[this.ItemIDs.length - 1];
+		this.removeRecord($item_id);
+	}
+}
+
 SimpleGrid.prototype.updateTotals = function () {
 	// prototype
 }