Found in X.org commit:

 commit d5bf6f95f31037bd49b11348b500c3c13b7e0c99
 Author: Keith Packard <keithp@keithp.com>
 Date:   Thu Oct 4 14:42:37 2012 -0700

    Fix FlushClient to write extraBuf when provided (regression fix)

    In commit:

        commit 092c57ab173c8b71056f6feb3b9d04d063a46579
        Author: Adam Jackson <ajax@redhat.com>
        Date:   Fri Jun 17 14:03:01 2011 -0400

            os: Hide the Connection{In,Out}put implementation details
Reviewed-by: Daniel Stone <daniel@fooishbar.org>
Signed-off-by: Adam Jackson <ajax@redhat.com>

    the check for an empty output buffer was moved from one calling
    location into the FlushClient implementation itself. However, this
    neglected the possibility that additional data, in the form of
    'extraBuf' would be passed to FlushClient from other code paths. If the
    output buffer happened to be empty at that time, the extra data would
    never be written to the client.

    This is fixed by checking the total data to be written, which includes
    both pending and extra data, instead of just the pending data.
Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Julien Cristau <jcristau@debian.org>
Backported-to-NX-by: Mike Gabriel <mike.gabriel@das-netzwerkteam.de>

 Backported from X.org:

 commit 9bf46610a9d20962854016032de4567974e87957
 Author: Chris Wilson <chris@chris-wilson.co.uk>
 Date:   Fri Jun 21 22:58:31 2013 +0100

    os: Immediately queue initial WriteToClient

    If we immediately put the WriteToClient() buffer into the socket's write
    queue, not only do we benefit from sending the response back to client
    earlier, but we also avoid the overhead of copying the data into our own
    staging buffer and causing extra work in the next select(). The write is
    effectively free as typically we may only send one reply per client per
    select() call, so the cost of the FlushClient() is the same.

    shmget10:   26400 -> 110000
    getimage10: 25000 -> 108000

    shmget500:   3160 -> 13500
    getimage500: 1000 -> 1010

    The knock-on effect is that on a mostly idle composited desktop, the CPU
    overhead is dominated by the memmove in WriteToClient, which is in turn
    eliminated by this patch.
Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Backported-to-NX-by: Mike Gabriel <mike.gabriel@das-netzwerkteam.de>

 Completing the below X.org commit:

 commit a3a40291330bad10401fe2bcdbc097ce742b026a
 Author: Keith Packard <keithp@keithp.com>
 Date:   Mon Sep 21 07:16:16 2015 +0100

    os/xdmcp: Remove dead 'restart' code

    The X server used to wait for the user to hit a key or move the mouse
    before restarting the session after a keepalive failure. This,
    presumably, was to avoid having the X server continuously spew XDMCP
    protocol on the network while the XDM server was dead.

    Switching into this state was removed from the server some time before
    XFree86 4.3.99.16, so the remaining bits of code have been dead for
    over a decade, and no-one ever noticed.
Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Keith Packard <keithp@keithp.com>
Backported-to-NX-by: Mike Gabriel <mike.gabriel@das-netzwerkteam.de>

Attributes GH PR #398: https://github.com/ArcticaProject/nx-libs/pull/398

CapsLock and NumLock will only be taken into account for keystrokes
that explicitly require them. This is implemented for convenience and
fixes ArcticaProject/nx-libs#397

Attributes GH PR #331: https://github.com/ArcticaProject/nx-libs/pull/331

 Backported from X.org:

 commit ce6546337487c052b5dd3c04d3d8d4b09d691c3d
 Author: Keith Packard <keithp@keithp.com>
 Date:   Tue May 31 09:38:17 2016 -0700

    os: Initialize NotifyFds earlier in startup

    If the server calls AbortServer during the first-time initialization
    (which can happen if you start the server on an already using
    DISPLAY), then the dbus code will shut down and call the notify fd
    interface. If the notify fd list hasn't been initialized, the server
    will crash.
Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Backported-to-NX-by: Mike Gabriel <mike.gabriel@das-netzwerkteam.de>

os: Implement support for NotifyFd X_NOTIFY_WRITE and removal of AddEnabledDevices/RemoveEnabledDevices

 Backported from X.org:

 commit be5a513fee6cbf29ef7570e57eb0436d70fbd88c
 Author: Keith Packard <keithp@keithp.com>
 Date:   Mon Dec 7 15:12:14 2015 -0800

    Remove AddEnabledDevice and AddGeneralSocket APIs

    All uses of these interfaces should instead be using the NotifyFd API
    instead.
Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>

 commit 4020aacd1fc5b9c63369f011aeb9120af9c55218
 Author: Keith Packard <keithp@keithp.com>
 Date:   Wed Nov 11 22:02:03 2015 -0800

    os: Implement support for NotifyFd X_NOTIFY_WRITE

    This adds the ability to be notified when a file descriptor is
    available for writing.
Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Keith Packard <keithp@keithp.com>
Backported-to-NX-by: Mike Gabriel <mike.gabriel@das-netzwerkteam.de>

Move the code for resetting the DPMS mode in response to input events, from WaitForSomething to mieqProcessInputEvents.

 Backported from X.org:

 commit 3b5b7ef5c2ab1d196806f6359e0972fd78d204dd
 Author: Fredrik Höglund <fredrik@kde.org>
 Date:   Wed Jan 3 21:05:35 2007 +0100

    Move the code for resetting the DPMS mode in response to input events,
    from WaitForSomething to mieqProcessInputEvents.

    mieqProcessInputEvents already handles resetting the screen saver.
Backported-to-NX-by: Mike Gabriel <mike.gabriel@das-netzwerkteam.de>

 Inspired by X.org commit:

 commit 55c2e1a3aa587c58a74066724e11e30b3df267b8
 Author: Keith Packard <keithp@keithp.com>
 Date:   Mon Dec 7 15:11:33 2015 -0800

    xnest: Use SetNotifyFd to receive events
Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>

 Backported from X.org:

 commit 0c41b7af4ab0c8d22b88f201293f59524d1e7317
 Author: Keith Packard <keithp@keithp.com>
 Date:   Wed Nov 11 22:02:02 2015 -0800

    os: Add NotifyFd interfaces

    This provides a callback-based interface to monitor file
    descriptors beyond the usual client and device interfaces.

    Modules within the server using file descriptors for reading and/or
    writing can call

        Bool SetNotifyFd(int fd, NotifyFdProcPtr notify_fd, int mask, void *data);

    mask can be any combination of X_NOTIFY_READ and X_NOTIFY_WRITE.

    When 'fd' becomes readable or writable, the notify_fd function will be
    called with the 'fd', the ready conditions and 'data' values as arguments,

    When the module no longer needs to monitor the fd, it will call

        void RemoveNotifyFd(int fd);

    RemoveNotifyFd may be called from the notify function.
Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Keith Packard <keithp@keithp.com>
Backported-to-NX-by: Mike Gabriel <mike.gabriel@das-netzwerkteam.de>

 Backported from X.org:

 commit db1089eafc1c5371fa0030202de588d2e2b4f8e5
 Author: Keith Packard <keithp@keithp.com>
 Date:   Mon Sep 21 07:16:17 2015 +0100

    os/xdmcp: Just send XDMCP keepalive packets once every three minutes

    There was a complicated scheme to increase the time between keepalives
    from 3 minutes up to as much as 24 hours in an attempt to reduce
    network traffic from idle X terminals. X terminals receiving X
    traffic, or receiving user input would use the 3 minute value; X
    terminals without any network traffic would use a longer value.

    However, this was actually broken -- any activity in the X server,
    either client requests or user input, would end up resetting the
    keepalive timeout, so a user mashing on the keyboard would never
    discover that the XDMCP master had disappeared and have the session
    terminated, which was precisely the design goal of the XDMCP keepalive
    mechanism.

    Instead of attempting to fix this, accept the cost of a pair of XDMCP
    packets once every three minutes and just perform keepalives
    regularly.

    This will also make reworking the block and wakeup handler APIs to
    eliminate select masks easier.
Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Keith Packard <keithp@keithp.com>
Backported-to-NX-by: Mike Gabriel <mike.gabriel@das-netzwerkteam.de>

Attributes GH PR #392: https://github.com/ArcticaProject/nx-libs/pull/392

Default is ctrl-alt-k

Do not use map before calling parse_keystroke_file() since it will malloc map.

Correctly use constant for unused structs instead of implicitly
setting it through calloc().

Unclear why they have been merged at all.

Code could not distinguish between ctrl-alt-shift and ctrl-alt.

Fixes ArcticaProject/nx-libs#395

Both use the same keystroke 'f' (with different modifiers) for a very
similar function.

We have defined them, so use them!

for better readability