Checks to see if the default version of wxPython is greater-than
    or equal to `minVersion`.  If not then it will try to find an
    installed version that is >= minVersion.  If none are available
    then a message is displayed that will inform the user and will
    offer to open their web browser to the wxPython downloads page,
    and will then exit the application.

def ensureMinimal(minVersion, optionsRequired=False):
    """
    Checks to see if the default version of wxPython is greater-than
    or equal to `minVersion`.  If not then it will try to find an
    installed version that is >= minVersion.  If none are available
    then a message is displayed that will inform the user and will
    offer to open their web browser to the wxPython downloads page,
    and will then exit the application.
    """
    assert type(minVersion) == str

    # ensure that wxPython hasn't been imported yet.
    if sys.modules.has_key('wx') or sys.modules.has_key('wxPython'):
        raise AlreadyImportedError("wxversion.ensureMinimal() must be called before wxPython is imported")

    bestMatch = None
    minv = _wxPackageInfo(minVersion)

    # check the default version first
    defaultPath = _find_default()
    if defaultPath:
        defv = _wxPackageInfo(defaultPath, True)
        if defv >= minv and minv.CheckOptions(defv, optionsRequired):
            bestMatch = defv

    # if still no match then check look at all installed versions
    if bestMatch is None:
        installed = _find_installed()
        # The list is in reverse sorted order, so find the first
        # one that is big enough and optionally matches the
        # options
        for inst in installed:
            if inst >= minv and minv.CheckOptions(inst, optionsRequired):
                bestMatch = inst
                break

    # if still no match then prompt the user
    if bestMatch is None:
        if _EM_DEBUG: # We'll do it this way just for the test code below
            raise VersionError("Requested version of wxPython not found")
        
        import wx, webbrowser
        versions = "\n".join(["      "+ver for ver in getInstalled()])
        app = wx.App()
        result = wx.MessageBox("This application requires a version of wxPython "
                               "greater than or equal to %s, but a matching version "
                               "was not found.\n\n"
                               "You currently have these version(s) installed:\n%s\n\n"
                               "Would you like to download a new version of wxPython?\n"
                               % (minVersion, versions),
                      "wxPython Upgrade Needed", style=wx.YES_NO)
        if result == wx.YES:
            webbrowser.open(UPDATE_URL)
        app.MainLoop()
        sys.exit()

    sys.path.insert(0, bestMatch.pathname)
    # q.v. Bug #1409256
    path64 = re.sub('/lib/','/lib64/',bestMatch.pathname)
    if os.path.isdir(path64):
        sys.path.insert(0, path64)
    global _selected
    _selected = bestMatch