Index: uspace/lib/gui/window.c
===================================================================
--- uspace/lib/gui/window.c	(revision f9b2cb4cf365498e1fe141b1aa66950fbc3dcb17)
+++ uspace/lib/gui/window.c	(revision bdfdc51cf6c5f6efd8f390b380b3a7ea368992af)
@@ -591,6 +591,6 @@
 }
 
-window_t *window_open(const char *winreg, window_flags_t flags,
-    const char *caption)
+window_t *window_open(const char *winreg, const void *data,
+    window_flags_t flags, const char *caption)
 {
 	window_t *win = (window_t *) malloc(sizeof(window_t));
@@ -604,5 +604,5 @@
 	fibril_mutex_initialize(&win->guard);
 	
-	widget_init(&win->root, NULL);
+	widget_init(&win->root, NULL, data);
 	win->root.window = win;
 	win->root.destroy = root_destroy;