Fix exception on exit in some case, sequel of an earlier cleanup commit I couldn't find back. Disconnecting the event is apparently the way to go. https://wiki.wxpython.org/Surviving%20with%20wxEVT%20KILL%20FOCUS%20under%20Microsoft%20Windows
<xsd:attribute name="Command" type="xsd:string" use="optional" default="make -C %(buildpath)s all BEREMIZSRC=%(src)s BEREMIZCFLAGS=%(cflags)s MD5=%(md5)s USE_BEREMIZ=1 FROM_BEREMIZ=1"/>