bug#24420: 25.1.50; Work around terminal differences for bracketed-paste/mouse-2

[Philipp Stephani]

There are several terminals that announce themselves as XTerm and
partially implement the XTerm control sequences
(http://invisible-island.net/xterm/ctlseqs/ctlseqs.html), but have some
slightly different behavior.  I've tried out XTerm, HTerm, and
gnome-terminal, and found the following behavior differences:

- XTerm sends xterm-paste (ESC [ 200~ ... ESC [ 201~) if
  xterm-mouse-mode is disabled.  If xterm-mouse-mode is enabled, it
  sends down-mouse-2 + up-mouse-2 using SGR coordinates (ESC [<1;x;yM
  ESC [<1;x;ym), which gets translated to mouse-yank-primary.

- Gnome Terminal sends xterm-paste if xterm-mouse-mode is disabled.  If
  xterm-mouse-mode is enabled, it only sends down-mouse-2 using SGR
  coordinates, which is ignored by Emacs.

- HTerm doesn't use bracketed paste mode if xterm-mouse-mode is disabled
  (i.e. pasted text gets inserted using individual
  self-insert-commands).  If xterm-mouse-mode is enabled, it uses both
  (!) down-mouse-2 + down-mouse-up (using basic coordinates) and then a
  bracketed paste.

The HTerm and Gnome-Terminal behaviors are probably bugs, and I'll try
to get them fixed.  However, maybe we want to work around these issues
on the Emacs side, e.g. by not requiring an up-mouse-2 if
xterm-mouse-mode is enabled.


In GNU Emacs 25.1.50.4 (x86_64-unknown-linux-gnu, GTK+ Version 3.10.8)
 of 2016-09-05 built on unknown
Repository revision: 6acff25280dbb97b5e9ddfd872b33ceb36b0470a
Windowing system distributor 'The X.Org Foundation', version 11.0.11501000
System Description:     Ubuntu 14.04 LTS

Configured using:
 'configure --with-modules'

Configured features:
XPM JPEG TIFF GIF PNG SOUND GSETTINGS NOTIFY GNUTLS FREETYPE XFT ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11 MODULES

Important settings:
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message subr-x puny seq byte-opt gv
bytecomp byte-compile cl-extra help-mode cconv cl-loaddefs pcase cl-lib
dired dired-loaddefs format-spec rfc822 mml easymenu mml-sec
password-cache epa derived epg epg-config gnus-util rmail rmail-loaddefs
mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils
mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr
mail-utils time-date mule-util tooltip eldoc electric uniquify
ediff-hook vc-hooks lisp-float-type mwheel term/x-win x-win
term/common-win x-dnd tool-bar dnd fontset image regexp-opt fringe
tabulated-list newcomment elisp-mode lisp-mode prog-mode register page
menu-bar rfn-eshadow timer select scroll-bar mouse jit-lock font-lock
syntax facemenu font-core term/tty-colors frame cl-generic cham georgian
utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao korean
japanese eucjp-ms cp51932 hebrew greek romanian slovak czech european
ethiopic indian cyrillic chinese charscript case-table epa-hook
jka-cmpr-hook help simple abbrev obarray minibuffer cl-preloaded nadvice
loaddefs button faces cus-face macroexp files text-properties overlay
sha1 md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote inotify dynamic-setting
system-font-setting font-render-setting move-toolbar gtk x-toolkit x
multi-tty make-network-process emacs)

Memory information:
((conses 16 97721 6855)
 (symbols 48 20654 0)
 (miscs 40 325 144)
 (strings 32 17939 4381)
 (string-bytes 1 588434)
 (vectors 16 13774)
 (vector-slots 8 451984 3705)
 (floats 8 183 31)
 (intervals 56 199 0)
 (buffers 976 12)
 (heap 1024 32176 1173))

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