diff --git a/extensions/window-numbering b/extensions/window-numbering
new file mode 160000
index 000000000..0b4cf9b2e
--- /dev/null
+++ b/extensions/window-numbering
@@ -0,0 +1 @@
+Subproject commit 0b4cf9b2e0f564771815f19a6b6293f923085d9b