Set the focus to the html display window

if the help frame comes to the front.
    With this, you can use context sensitive
    help systems without the mouse.


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@15661 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/html/helpfrm.h

@@ -164,6 +164,7 @@ protected:
     void OnSearch(wxCommandEvent& event);
     void OnBookmarksSel(wxCommandEvent& event);
     void OnCloseWindow(wxCloseEvent& event);
+    void OnActivate(wxActivateEvent& event);
 
     // Images:
     enum {