diff --git a/app/widgets/gimpwidgets-utils.c b/app/widgets/gimpwidgets-utils.c
index b66a6d63e1..dd587e2f22 100644
--- a/app/widgets/gimpwidgets-utils.c
+++ b/app/widgets/gimpwidgets-utils.c
@@ -2585,7 +2585,17 @@ gimp_window_set_transient_cb (GtkWidget   *window,
       transient_set = TRUE;
     }
 #endif
-#ifdef GDK_WINDOWING_WIN32
+  /* Cross-process transient-for is broken in gdk/win32. It causes hangs of the
+   * main process and we still don't know why.
+   * If it eventually is fixed to actually work, change this to a run-time check
+   * of GTK+ version. Remember to change also gimp_window_transient_on_mapped()
+   * in libgimp/gimpui.c
+   *
+   * Note: this hanging bug is still happening with GTK+3 as of mid-2023 with
+   * steps described in comment 4 in:
+   * https://bugzilla.gnome.org/show_bug.cgi?id=359538
+   */
+#if 0 && defined (GDK_WINDOWING_WIN32)
   if (! transient_set)
     {
       GdkWindow *parent;
diff --git a/libgimp/gimpui.c b/libgimp/gimpui.c
index af6d5046d1..73279450c5 100644
--- a/libgimp/gimpui.c
+++ b/libgimp/gimpui.c
@@ -389,7 +389,10 @@ gimp_window_transient_on_mapped (GtkWidget   *window,
       transient_set = TRUE;
     }
 #endif
-#ifdef GDK_WINDOWING_WIN32
+  /* To know why it is disabled on Win32, see gimp_window_set_transient_cb() in
+   * app/widgets/gimpwidgets-utils.c.
+   */
+#if 0 && defined (GDK_WINDOWING_WIN32)
   if (! transient_set)
     {
       GdkWindow *parent;