document wxRESIZE_BORDER side effect under Windows (see #9989)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@56684 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/dirdlg.h

@@ -25,8 +25,20 @@
            user.
     @endStyleTable
 
-    @note On Windows the new directory button is only available with recent
-          versions of the common dialogs.
+    Notice that @c wxRESIZE_BORDER has special side effect under recent (i.e.
+    later than Win9x) Windows where two different directory selection dialogs
+    are available and this style also implicitly selects the new version as the
+    old one always has fixed size. As the new version is almost always
+    preferable, it is recommended that @c wxRESIZE_BORDER style be always used.
+    This is the case if the dialog is created with the default style value but
+    if you need to use any additional styles you should still specify @c
+    wxDD_DEFAULT_STYLE unless you explicitly need to use the old dialog version
+    under Windows. E.g. do
+    @code
+        wxDirDialog dlg(NULL, "Choose input directory", "",
+                        wxDD_DEFAULT_STYLE | wxDD_DIR_MUST_EXIST);
+    @endcode
+    instead of just using @c wxDD_DIR_MUST_EXIST style alone.
 
     @library{wxcore}
     @category{cmndlg}