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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#! gmake

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yml := ../../yml2

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ysl2files := $(wildcard *.ysl2)

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xsltfiles := $(patsubst %.ysl2, %.xslt, $(ysl2files))

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all:$(xsltfiles)

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%.xslt: %.ysl2 yslt_noindent.yml2

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	$(yml)/yml2c -I $(yml) $< -o $@.tmp

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	xmlstarlet fo $@.tmp > $@

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	rm $@.tmp

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clean:

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	rm -f $(xsltfiles)