Enable the HWND of the task dialog to be fetched with GetHandle if it is being used.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@69041 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/progdlg.h

@@ -47,6 +47,8 @@ public:
     // Must provide overload to avoid hiding it (and warnings about it)
     virtual void Update() { wxGenericProgressDialog::Update(); }
 
+    virtual WXWidget GetHandle() const;
+
 private:
     // Performs common routines to Update() and Pulse(). Requires the
     // shared object to have been entered.