bug#22918: 25.1.50; Scrolling upwards with xwidget-webkit-browse-url

[Shayan Pirani]

Bug Description: When browsing a web page with
xwidget-webkit-browse-url, pressing "M-v" to scroll upwards gives the
following error message: "Wrong type argument: wholenump, -50", and the
page is not scrolled up. One solution to this problem is to make a small
change in xwidget.c: inside the "xwidget-set-adjustment" definition,
change CHECK_NATNUM to lisp_h_CHECK_NUMBER, which will allow the value
argument to be a negative integer.

Steps to reproduce bug:
1) Start emacs with "emacs -q"
2) M-x xwidget-webkit-browse-url
3) Navigate to a web page
4) Press C-v to scroll down the page (this works fine)
5) Press M-v to try scrolling upwards (this will give the above error)



In GNU Emacs 25.1.50.2 (x86_64-pc-linux-gnu, GTK+ Version 3.18.7)
 of 2016-03-05 built on latitude
Repository revision: 227ab51db6517bda1a557391bebaa7882b51963e
Windowing system distributor 'The X.Org Foundation', version 11.0.11801000
System Description:    Debian GNU/Linux testing-updates (sid)

Configured using:
 'configure --with-x-toolkit=gtk3 --with-xwidgets'

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND DBUS GSETTINGS NOTIFY
LIBXML2 FREETYPE XFT ZLIB TOOLKIT_SCROLL_BARS GTK3 X11 XWIDGETS

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

Major mode: Fundamental

Minor modes in effect:
  diff-auto-refine-mode: t
  recentf-mode: t
  global-hl-line-mode: t
  delete-selection-mode: t
  pdf-occur-global-minor-mode: t
  erc-services-mode: t
  erc-list-mode: t
  erc-menu-mode: t
  erc-autojoin-mode: t
  erc-ring-mode: t
  erc-networks-mode: t
  erc-pcomplete-mode: t
  erc-track-mode: t
  erc-match-mode: t
  erc-netsplit-mode: t
  erc-hl-nicks-mode: t
  erc-button-mode: t
  erc-fill-mode: t
  erc-stamp-mode: t
  erc-irccontrols-mode: t
  erc-noncommands-mode: t
  erc-move-to-prompt-mode: t
  erc-readonly-mode: t
  global-yascroll-bar-mode: t
  yascroll-bar-mode: t
  show-smartparens-global-mode: t
  show-smartparens-mode: t
  smartparens-global-mode: t
  smartparens-mode: t
  shackle-mode: t
  projectile-global-mode: t
  projectile-mode: t
  company-quickhelp-mode: t
  global-company-mode: t
  company-mode: t
  helm-mode: t
  shell-dirtrack-mode: t
  async-bytecomp-package-mode: t
  helm-flx-mode: t
  guide-key-mode: t
  global-flycheck-mode: t
  global-evil-surround-mode: t
  evil-surround-mode: t
  evil-escape-mode: t
  global-anzu-mode: t
  anzu-mode: t
  evil-leader-mode: t
  evil-mode: t
  global-undo-tree-mode: t
  undo-tree-mode: t
  evil-local-mode: t
  persp-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent messages:
Creating customization items...
Creating group...
Creating group entries...done
Creating customization items ...done
Resetting customization items...done
Creating customization setup...done
Custom-no-edit: You can’t edit this part of the Custom buffer
Mark saved where search started [2 times]
g g
SPC d k

Load-path shadows:
/home/bhai/.emacs.d/elpa/helm-20160304.713/helm-multi-match hides
/home/bhai/.emacs.d/elpa/helm-core-20160303.1321/helm-multi-match

Features:
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easy-mmode helm-source eieio-compat helm-multi-match helm-lib dired
dired-loaddefs helm-flx guide-key s ucs-normalize popwin gnugo-imgen
xpm-m2z artist picture reporter xpm gnugo flycheck find-func rx subr-x
seq expand-region text-mode-expansions er-basic-expansions
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edmacro kmacro cl ace-window avy ring solarized-dark-theme solarized
dash finder-inf info package epg-config url-handlers url-parse
auth-source cl-seq eieio byte-opt bytecomp byte-compile cl-extra
help-mode easymenu cconv eieio-core cl-macs gv eieio-loaddefs
cl-loaddefs pcase cl-lib password-cache url-vars 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 dbusbind inotify
dynamic-setting system-font-setting font-render-setting xwidget-internal
move-toolbar gtk x-toolkit x multi-tty make-network-process emacs)

Memory information:
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 (symbols 48 56336 1)
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 (strings 32 264787 155914)
 (string-bytes 1 7584333)
 (vectors 16 88733)
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 (heap 1024 107438 92607))