There are actually two different buffers in X and they are each used a bit differently. See here for an explanation: http://www.jwz.org/doc/x-cut-and-paste.htm

There are actually two different buffers in X and they are each used a bit differently. See here for an explanation: http://www.jwz.org/doc/x-cut-and-paste.html http://www.jwz.org/doc/x-cut-and-paste.html