don't crash when attempting to select hidden tree root (bug 1681118)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@45134 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/treectrl.cpp

@@ -1725,6 +1725,8 @@ void wxTreeCtrl::UnselectAll()
 
 void wxTreeCtrl::SelectItem(const wxTreeItemId& item, bool select)
 {
+    wxCHECK_RET( !IsHiddenRoot(item), _T("can't select hidden root item") );
+
     if ( m_windowStyle & wxTR_MULTIPLE )
     {
         ::SelectItem(GetHwnd(), HITEM(item), select);