[gtk+] Mention thread-safety issues

[Matthias Clasen <matthiasc src gnome org>]

commit f10f6b8b0c9787d5d394bcb73fcb3b85bf3c7567
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Sep 13 23:32:46 2009 -0400

    Mention thread-safety issues

 .../reference/gtk/migrating-ClientSideWindows.sgml |   13 ++++++++-----
 1 files changed, 8 insertions(+), 5 deletions(-)
---
diff --git a/docs/reference/gtk/migrating-ClientSideWindows.sgml b/docs/reference/gtk/migrating-ClientSideWindows.sgml
index 934c7b3..845e956 100644
--- a/docs/reference/gtk/migrating-ClientSideWindows.sgml
+++ b/docs/reference/gtk/migrating-ClientSideWindows.sgml
@@ -13,9 +13,12 @@
     longer correct to assume that each window has an associated XID.
     Code that makes this assumption can sometimes be fixed by calling
     gdk_window_ensure_native() on the windows in question.
-    Calling gdk_x11_drawable_get_xid() from the X11-specific API on a
-    non-native window will explicitly call gdk_window_ensure_native(),
-    so old code using this will continue to work.
+    Calling gdk_x11_drawable_get_xid() (or GDK_WINDOW_XID()) from the
+    X11-specific API on a non-native window will explicitly call
+    gdk_window_ensure_native(), so old code using this will continue to
+    work. A small gotcha is that the GDK_WINDOW_XID() call is no longer a
+    trivial accessor for the XID of the window, and thus must not be called
+    from another thread without taking locking precautions.
   </para>
 
   <para>
@@ -57,8 +60,8 @@
   <para>
     Due to a weird API in XClearArea the gdk_window_clear_area() call handled
     a specified width or height of zero to mean "to end of window" for
-    non-doublebuffered drawing. This has been changed to be consistent with
-    the docs and what happens in the doublebuffered case. All code in gtk+
+    non-double-buffered drawing. This has been changed to be consistent with
+    the docs and what happens in the double-buffered case. All code in GTK+
     that relied on this has been fixed, but it is possible (although unlikely)
     that third party applications rely on this. If you need to do this, just
     implement it yourself using gdk_drawable_get_size().