fix close button in system menu for AboutDialog on Windows


If SetEscapeId receives wx.ID_CLOSE as parameter, then on Windows with
wxPython 2.8 system close button in title bar stops working.
If wx.ID_CANCEL or wx.ID_OK is used in SetEscapeId call, then close
button works correctly.

                  <xsd:element name="Generic">
                    <xsd:complexType>
                      %(toolchain_makefile)s
                    </xsd:complexType>
                  </xsd:element>