added wxNavigationKeyEvent::IsBackward to be able to call wxWindow::Navigate(IsBackward) and not only Navigate(IsForward)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@28195 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/event.h

@@ -1797,6 +1797,7 @@ public:
 
     enum
     {
+        IsBackward = 0x0000,
         IsForward = 0x0001,
         WinChange = 0x0002
     };