fix problem with hidden FindInPou dialog with wxPython 3.0 on Windows

FindInPou.IsShown() returned True, but dialog was hidden.
At same time On GNU/Linux with wxPython 3.0 there wasn't such problem.
So it's Windows specific.

<?xml version="1.0" encoding="UTF-8"?>
<BeremizRoot URI_location="LOCAL://">
  <TargetType/>
</BeremizRoot>