This function may be used to know the hardware device that triggered
an event, it could resort to the master device in the few cases there's
not a direct hardware device to relate to the event (i.e.: crossing events
due to grabs)

Use GDK_WINDOW_XID() instead.

THis was done using sed, so there might be issues resulting to that.
Feel free to fix.

Try to do inclusions in the same sequence, more or less.

* _gdk_device_set_associated_device() did not allow NULL device
* GdkDisplay should dispose device manager to avoid devices
  trying to touch the display in finalize
* GdkDeviceManagerXI did not ref devices in id hash
* GdkDisplayX11 did not ref devices in ->input_devices

The keysyms create a lot of potential namespace conflicts for
C, and are especially problematic for introspection, where we take
constants into the namespace, so GDK_Display conflicts with GdkDisplay.

For C application compatiblity, add gdkkeysyms-compat.h which uses
the old names.

Just one user in GTK+ continues to use gdkkeysyms-compat.h, which is
the gtkimcontextsimple.c, since porting that requires porting more
custom Perl code.

https://bugzilla.gnome.org/show_bug.cgi?id=623845

This function makes a better replacement for
gdk_display_get_core_pointer(), wherever it might yet be needed, for
XI2 resorts to XIGetClientPointer(), for the others return the only
core pointer.

https://bugzilla.gnome.org/show_bug.cgi?id=621685