[gtk/docs-window-position] docs: Mention gtk_window_set_position() being gone

[Emmanuele Bassi <ebassi src gnome org>]

commit 0054f8bd746a4791120737f72e01183f57561cf9
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Fri Oct 8 12:27:24 2021 +0100

    docs: Mention gtk_window_set_position() being gone
    
    People search for it in the migration guide much more than other
    GdkSurface and GtkWindow methods.

 docs/reference/gtk/migrating-3to4.md | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)
---
diff --git a/docs/reference/gtk/migrating-3to4.md b/docs/reference/gtk/migrating-3to4.md
index 492e8628e4..2a0164fd7e 100644
--- a/docs/reference/gtk/migrating-3to4.md
+++ b/docs/reference/gtk/migrating-3to4.md
@@ -668,18 +668,21 @@ box children as necessary.
 ### Adapt to `GtkWindow` API changes
 
 Following the `GdkSurface` changes, a number of `GtkWindow` APIs that were
-X11-specific have been removed. This includes `gtk_window_set_geometry_hints()`,
-`gtk_window_set_gravity()`, `gtk_window_move()`, `gtk_window_parse_geometry()`,
+X11-specific have been removed. This includes `gtk_window_set_position()`,
+`gtk_window_set_geometry_hints()`, `gtk_window_set_gravity()`,
+`gtk_window_move()`, `gtk_window_parse_geometry()`,
 `gtk_window_set_keep_above()`, `gtk_window_set_keep_below()`,
 `gtk_window_begin_resize_drag()`, `gtk_window_begin_move_drag()`.
 Most likely, you should just stop using them. In some cases, you can
 fall back to using the underlying `GdkToplevel` APIs (for example,
-[method@Gdk.Toplevel.begin_resize]).
+[`method@Gdk.Toplevel.begin_resize`]); alternatively, you will need to get
+the native windowing system surface from the `GtkWindow` and call platform
+specific API.
 
 The APIs for controlling `GtkWindow` size have changed to be better aligned
 with the way size changes are integrated in the frame cycle. `gtk_window_resize()`
 and `gtk_window_get_size()` have been removed. Instead, use
-[method@Gtk.Window.set_default_size] and [method@Gtk.Window.get_default_size].
+[`method@Gtk.Window.set_default_size`] and [`method@Gtk.Window.get_default_size`].
 
 ### Adapt to `GtkHeaderBar` and `GtkActionBar` API changes