beremiz

fix deprecation warnings about accessing properties m_x, m_y of wxKeyEvent

/home/beremiz/beremiz/controls/PouInstanceVariablesPanel.py:354: wxPyDeprecationWarning: Accessing deprecated property.
event.m_x = size.width / 2
<?xml version='1.0' encoding='utf-8'?>
<BaseParams xmlns:xsd="http://www.w3.org/2001/XMLSchema" IEC_Channel="2" Name="py_ext_0"/>