fix hangs on mouse selection in case if wxPython uses wxWidgets with GTK3+ support
This is default configuration on Debian Buster+ and Ubuntu 18.04+.
Probably it'll fix completely problem with 'clipboard already open'
described in the previous commit 5ce6d08f ("make clipboard open minimal time as wxPython documentation recommends")
#!/usr/bin/env python
# -*- coding: utf-8 -*-
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