diff --git a/dlls/user32/win.c b/dlls/user32/win.c
index a22b80da6a9..a5d1a640335 100644
--- a/dlls/user32/win.c
+++ b/dlls/user32/win.c
@@ -287,76 +287,6 @@ static HWND *list_window_children( HDESK desktop, HWND hwnd, UNICODE_STRING *cla
 }
 
 
-/*******************************************************************
- *           list_window_parents
- *
- * Build an array of all parents of a given window, starting with
- * the immediate parent. The array must be freed with HeapFree.
- */
-static HWND *list_window_parents( HWND hwnd )
-{
-    WND *win;
-    HWND current, *list;
-    int i, pos = 0, size = 16, count;
-
-    if (!(list = HeapAlloc( GetProcessHeap(), 0, size * sizeof(HWND) ))) return NULL;
-
-    current = hwnd;
-    for (;;)
-    {
-        if (!(win = WIN_GetPtr( current ))) goto empty;
-        if (win == WND_OTHER_PROCESS) break;  /* need to do it the hard way */
-        if (win == WND_DESKTOP)
-        {
-            if (!pos) goto empty;
-            list[pos] = 0;
-            return list;
-        }
-        list[pos] = current = win->parent;
-        WIN_ReleasePtr( win );
-        if (!current) return list;
-        if (++pos == size - 1)
-        {
-            /* need to grow the list */
-            HWND *new_list = HeapReAlloc( GetProcessHeap(), 0, list, (size+16) * sizeof(HWND) );
-            if (!new_list) goto empty;
-            list = new_list;
-            size += 16;
-        }
-    }
-
-    /* at least one parent belongs to another process, have to query the server */
-
-    for (;;)
-    {
-        count = 0;
-        SERVER_START_REQ( get_window_parents )
-        {
-            req->handle = wine_server_user_handle( hwnd );
-            wine_server_set_reply( req, list, (size-1) * sizeof(user_handle_t) );
-            if (!wine_server_call( req )) count = reply->count;
-        }
-        SERVER_END_REQ;
-        if (!count) goto empty;
-        if (size > count)
-        {
-            /* start from the end since HWND is potentially larger than user_handle_t */
-            for (i = count - 1; i >= 0; i--)
-                list[i] = wine_server_ptr_handle( ((user_handle_t *)list)[i] );
-            list[count] = 0;
-            return list;
-        }
-        HeapFree( GetProcessHeap(), 0, list );
-        size = count + 1;
-        if (!(list = HeapAlloc( GetProcessHeap(), 0, size * sizeof(HWND) ))) return NULL;
-    }
-
- empty:
-    HeapFree( GetProcessHeap(), 0, list );
-    return NULL;
-}
-
-
 /*******************************************************************
  *           send_parent_notify
  */
@@ -3029,24 +2959,8 @@ BOOL WINAPI IsWindowVisible( HWND hwnd )
  */
 BOOL WIN_IsWindowDrawable( HWND hwnd, BOOL icon )
 {
-    HWND *list;
-    BOOL retval = TRUE;
-    int i;
-    LONG style = GetWindowLongW( hwnd, GWL_STYLE );
-
-    if (!(style & WS_VISIBLE)) return FALSE;
-    if ((style & WS_MINIMIZE) && icon && GetClassLongPtrW( hwnd, GCLP_HICON ))  return FALSE;
-
-    if (!(list = list_window_parents( hwnd ))) return TRUE;
-    if (list[0])
-    {
-        for (i = 0; list[i+1]; i++)
-            if ((GetWindowLongW( list[i], GWL_STYLE ) & (WS_VISIBLE|WS_MINIMIZE)) != WS_VISIBLE)
-                break;
-        retval = !list[i+1] && (list[i] == GetDesktopWindow());  /* top message window isn't visible */
-    }
-    HeapFree( GetProcessHeap(), 0, list );
-    return retval;
+    /* FIXME: move callers to win32u */
+    return NtUserCallHwndParam( hwnd, icon, NtUserIsWindowDrawable );
 }
 
 
diff --git a/dlls/win32u/window.c b/dlls/win32u/window.c
index e13107d1d64..7b5a6b3da03 100644
--- a/dlls/win32u/window.c
+++ b/dlls/win32u/window.c
@@ -625,6 +625,35 @@ static BOOL is_window_visible( HWND hwnd )
     return retval;
 }
 
+/***********************************************************************
+ *           is_window_drawable
+ *
+ * hwnd is drawable when it is visible, all parents are not
+ * minimized, and it is itself not minimized unless we are
+ * trying to draw its default class icon.
+ */
+static BOOL is_window_drawable( HWND hwnd, BOOL icon )
+{
+    HWND *list;
+    BOOL retval = TRUE;
+    int i;
+    LONG style = get_window_long( hwnd, GWL_STYLE );
+
+    if (!(style & WS_VISIBLE)) return FALSE;
+    if ((style & WS_MINIMIZE) && icon && get_class_long_ptr( hwnd, GCLP_HICON, FALSE ))  return FALSE;
+
+    if (!(list = list_window_parents( hwnd ))) return TRUE;
+    if (list[0])
+    {
+        for (i = 0; list[i+1]; i++)
+            if ((get_window_long( list[i], GWL_STYLE ) & (WS_VISIBLE|WS_MINIMIZE)) != WS_VISIBLE)
+                break;
+        retval = !list[i+1] && (list[i] == user_callbacks->pGetDesktopWindow());  /* top message window isn't visible */
+    }
+    free( list );
+    return retval;
+}
+
 static LONG_PTR get_win_data( const void *ptr, UINT size )
 {
     if (size == sizeof(WORD))
@@ -1015,6 +1044,9 @@ ULONG_PTR WINAPI NtUserCallHwndParam( HWND hwnd, DWORD_PTR param, DWORD code )
         return get_window_word( hwnd, param );
     case NtUserIsChild:
         return is_child( hwnd, UlongToHandle(param) );
+    /* temporary exports */
+    case NtUserIsWindowDrawable:
+        return is_window_drawable( hwnd, param );
     default:
         FIXME( "invalid code %u\n", code );
         return 0;
diff --git a/include/ntuser.h b/include/ntuser.h
index 20fa61bacec..3fca830d5b2 100644
--- a/include/ntuser.h
+++ b/include/ntuser.h
@@ -161,6 +161,8 @@ enum
     NtUserGetWindowThread,
     NtUserGetWindowWord,
     NtUserIsChild,
+    /* temporary exports */
+    NtUserIsWindowDrawable,
 };
 
 /* color index used to retrieve system 55aa brush */