restored accidentally removed code which deselects the previously selected button in SetSelection()

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@31028 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/radiobox.cpp

@@ -378,6 +378,11 @@ void wxRadioBox::SetSelection(int N)
 {
     wxCHECK_RET( (N >= 0) && (N < GetCount()), wxT("invalid radiobox index") );
 
+    // unselect the old button
+    if ( m_selectedButton != wxNOT_FOUND )
+        ::SendMessage((*m_radioButtons)[m_selectedButton], BM_SETCHECK, 0, 0L);
+
+    // and select the new one
     ::SendMessage((*m_radioButtons)[N], BM_SETCHECK, 1, 0L);
 
     m_selectedButton = N;