How river currently sets this isn't really in accordance with the spirit
of the protocol. It was originally done this way to get gtk3 windows to
look a little bit better with borders drawn around them. However, I've
come to believe that river shouldn't just ignore standards like this.
The right way to do things would be to either implement the
xdg-decoration protocol for gtk properly or to be pragmatic and accept
some programs are intended to be used with CSD and that's OK.
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