diff --git a/binaries/data/mods/official/gui/test/functions_list.js b/binaries/data/mods/official/gui/test/functions_list.js
new file mode 100644
index 0000000000..200e72fc00
--- /dev/null
+++ b/binaries/data/mods/official/gui/test/functions_list.js
@@ -0,0 +1,53 @@
+/*
+ ***************************************
+ functions_list.js
+
+ Functions to manipulate objects with
+ a 'list' property. It is important to
+ do this and not manually to ensure that
+ the selection is updated properly.
+ 
+ ***************************************
+*/
+
+function removeItem(objectName, pos)
+{
+	var list = getGUIObjectByName(objectName).list;
+	var selected = getGUIObjectByName(objectName).selected;
+	list.splice(pos, 1);
+
+	getGUIObjectByName(objectName).list = list;
+
+	// It is important that we're setting the new selection *after*
+	//  the list is already updated.
+
+	// Update the selected so the same element remains selected
+	if (selected == pos)
+	{
+		getGUIObjectByName(objectName).selected = -1;
+	}
+	else
+	if (selected > pos)
+	{
+		getGUIObjectByName(objectName).selected = selected - 1;
+	}
+}
+
+function addItem(objectName, pos, value)
+{
+	var list = getGUIObjectByName(objectName).list;
+	var selected = getGUIObjectByName(objectName).selected;
+	list.splice(pos, 0, value);
+
+	getGUIObjectByName(objectName).list = list;
+
+	// It is important that we're setting the new selection *after*
+	//  the list is already updated.
+
+	// Update the selected so the same element remains selected
+	if (selected >= pos)
+	{
+		getGUIObjectByName(objectName).selected = selected + 1;
+	}
+
+}
\ No newline at end of file