Use new style directory selection dialog under Vista and later.

Use IFileDialog in wxDirDialog implementation if possible, it shows a much
more user-friendly dialog than the one used by SHBrowseForFolder().

Closes #11401.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@71201 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/dirdlg.h

@@ -28,6 +28,11 @@ public:
     virtual int ShowModal();
 
 private:
+    // The real implementations of ShowModal(), used for Windows versions
+    // before and since Vista.
+    int ShowSHBrowseForFolder(WXHWND owner);
+    int ShowIFileDialog(WXHWND owner);
+
     DECLARE_DYNAMIC_CLASS_NO_COPY(wxDirDialog)
 };