diff --git a/dix/dix_priv.h b/dix/dix_priv.h
index 44229bc08..81d33ad92 100644
--- a/dix/dix_priv.h
+++ b/dix/dix_priv.h
@@ -38,6 +38,19 @@ extern HWEventQueuePtr checkForInput[2];
  /* -retro mode */
 extern Bool party_like_its_1989;
 
+/*
+ * @brief callback right after one screen's root window has been initialized
+ *
+ * For extensions that need additional setup after root window is completely
+ * initialized (eg. possible to create new windows), but before any client
+ * can connect. Called once per screen (supplied as arg) - the screen's
+ * CreateWindow proc already had been called on the root window.
+ *
+ * Not for DDXs / drivers: those already informed by screen's CreateWindow
+ * proc being called on the root window.
+ */
+extern CallbackListPtr PostInitRootWindowCallback;
+
 static inline _X_NOTSAN Bool
 InputCheckPending(void)
 {
diff --git a/dix/main.c b/dix/main.c
index 5dbee7fdb..b02854915 100644
--- a/dix/main.c
+++ b/dix/main.c
@@ -130,6 +130,7 @@ Equipment Corporation.
 extern void Dispatch(void);
 
 CallbackListPtr RootWindowFinalizeCallback = NULL;
+CallbackListPtr PostInitRootWindowCallback = NULL;
 
 int
 dix_main(int argc, char *argv[], char *envp[])
@@ -251,8 +252,10 @@ dix_main(int argc, char *argv[], char *envp[])
             PanoramiXConsolidate();
 #endif /* XINERAMA */
 
-        for (i = 0; i < screenInfo.numScreens; i++)
+        for (i = 0; i < screenInfo.numScreens; i++) {
             InitRootWindow(screenInfo.screens[i]->root);
+            CallCallbacks(&PostInitRootWindowCallback, screenInfo.screens[i]);
+        }
 
         InitCoreDevices();
         InitInput(argc, argv);