bug#26855: 25.2; Menus off screen, gtk errors

[martin rudalics]

> Menus (e.g. from the menubar) are appearing off screen. Using Fedora 25 in 
VirtualBox
> 5.1.22. with guest additions. There are a lot of gtk errors when opening
> a menu. GTK error messages included below. This started with either
> emacs 25 or Fedora 25 upgrade.
>
> In GNU Emacs 25.2.1 (x86_64-redhat-linux-gnu, GTK+ Version 3.22.11)
>   of 2017-04-25 built on buildhw-05.phx2.fedoraproject.org
> Windowing system distributor 'The Cygwin/X Project', version 11.0.11902000
> Configured using:
>   'configure --build=x86_64-redhat-linux-gnu
>   --host=x86_64-redhat-linux-gnu --program-prefix=
>   --disable-dependency-tracking --prefix=/usr --exec-prefix=/usr
>   --bindir=/usr/bin --sbindir=/usr/sbin --sysconfdir=/etc
>   --datadir=/usr/share --includedir=/usr/include --libdir=/usr/lib64
>   --libexecdir=/usr/libexec --localstatedir=/var
>   --sharedstatedir=/var/lib --mandir=/usr/share/man
>   --infodir=/usr/share/info --with-dbus --with-gif --with-jpeg --with-png
>   --with-rsvg --with-tiff --with-xft --with-xpm --with-x-toolkit=gtk3
>   --with-gpm=no --with-xwidgets build_alias=x86_64-redhat-linux-gnu
>   host_alias=x86_64-redhat-linux-gnu 'CFLAGS=-DMAIL_USE_LOCKF -O2 -g
>   -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2
>   -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4
>   -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1
>   -m64 -mtune=generic' LDFLAGS=-Wl,-z,relro
>   PKG_CONFIG_PATH=:/usr/lib64/pkgconfig:/usr/share/pkgconfig'

Looks bad.  Hopefully this is covered by the fix for bug#25851, see

https://debbugs.gnu.org/cgi/bugreport.cgi?bug=25851

In Message#218 of that thread you can find a patch
(x_gtk_use_window_move.diff) I proposed for Emacs 25.  If you can build
Emacs yourself, please try it.

martin