Catch 'clipboard already open' errors in editors

Apparently following commits have not fixed the problem completely,
because it still happens (although not so often).

changeset: 2019:b8f795bdfe9f
user: Andrey Skvortsov <andrej.skvortzov@gmail.com>
date: Fri May 25 17:40:29 2018 +0300
summary: fix hangs on mouse selection in case if wxPython uses wxWidgets with GTK3+ support

changeset: 2018:5ce6d08ff2c7
user: Andrey Skvortsov <andrej.skvortzov@gmail.com>
date: Fri May 25 17:23:15 2018 +0300
summary: make clipboard open minimal time as wxPython documentation recommends

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                  <xsd:element name="Win32">

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                    <xsd:complexType>

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                      %(toolchain_gcc)s

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                    </xsd:complexType>

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                  </xsd:element>

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