doc file path for nxdialog was wrong

Fixes ArcticaProject/nx-libs#959

Attributes GH PR #940: https://github.com/ArcticaProject/nx-libs/pull/940

Setting nxagentDefaultWindow[pScreen->myNum] is pointless because it is
overwritten in the next code block...

setting a value for an attribute in the structure is pointless if you
do not set the valuemask accordingly. Adding the missing valuemask
code here would also be pointless because the valuemask is set to a fixed
value later on. Therefore we can drop this code here.

new code is easier to read

and not as a "private" window like all others.

We are not using it anywhere so let's disable it via a macro for now.

This only happened with certain window managers like mutter.

Fixes ArcticaProject/nx-libs#925

Not really sure why I introduced the client check years ago. Grabbed is
grabbed, so I don't see a reason implementing it this way.

Fixes ArcticaProject/nx-libs#925.

Attributes GH PR #942: https://github.com/ArcticaProject/nx-libs/pull/942

In compext Atom has the size of XlibAtom. Therefore calling functions
of Compext.c requires to use/pass XlibAtom. Same for Window/XlibWindow.

==15438==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7fffffffcdc0 at pc 0x5555556a81b5 bp 0x7fffffffcd10 sp 0x7fffffffcd08
WRITE of size 8 at 0x7fffffffcdc0 thread T0
    #0 0x5555556a81b4 in NXGetCollectedProperty nx-X11/programs/Xserver/hw/nxagent/compext/Compext.c:4124
    #1 0x5555557d0488 in nxagentCollectPropertyEvent nx-X11/programs/Xserver/hw/nxagent/Clipboard.c:1202
    #2 0x555555723340 in nxagentHandleCollectPropertyEvent nx-X11/programs/Xserver/hw/nxagent/Events.c:3923
    #3 0x55555571d4db in nxagentHandleProxyEvent nx-X11/programs/Xserver/hw/nxagent/Events.c:3007
    #4 0x55555571bb92 in nxagentHandleClientMessageEvent nx-X11/programs/Xserver/hw/nxagent/Events.c:2595
    #5 0x555555717dfc in nxagentDispatchEvents nx-X11/programs/Xserver/hw/nxagent/Events.c:1827
    #6 0x555555750813 in nxagentBlockHandler nx-X11/programs/Xserver/hw/nxagent/Handlers.c:437
    #7 0x5555556c1b5d in BlockHandler nx-X11/programs/Xserver/dix/dixutils.c:403
    #8 0x5555556d47ff in WaitForSomething nx-X11/programs/Xserver/os/WaitFor.c:232
    #9 0x555555665b22 in Dispatch nx-X11/programs/Xserver/hw/nxagent/NXdispatch.c:365
    #10 0x5555555ed760 in main nx-X11/programs/Xserver/dix/main.c:350
    #11 0x7ffff604909a in __libc_start_main ../csu/libc-start.c:308
    #12 0x5555555edc09 in _start (nx-X11/programs/Xserver/nxagent+0x99c09)

Address 0x7fffffffcdc0 is located in stack of thread T0 at offset 32 in frame
    #0 0x5555557d0324 in nxagentCollectPropertyEvent nx-X11/programs/Xserver/hw/nxagent/Clipboard.c:1190

  This frame has 5 object(s):
    [32, 36) 'atomReturnType' <== Memory access at offset 32 partially overflows this variable
    [96, 100) 'resultFormat'
    [160, 168) 'ulReturnItems'
    [224, 232) 'ulReturnBytesLeft'
    [288, 296) 'pszReturnData'
HINT: this may be a false positive if your program uses some custom stack unwind mechanism, swapcontext or vfork
      (longjmp and C++ exceptions *are* supported)
SUMMARY: AddressSanitizer: stack-buffer-overflow nx-X11/programs/Xserver/hw/nxagent/compext/Compext.c:4124 in NXGetCollectedProperty
...

Attributes GH PR #937: https://github.com/ArcticaProject/nx-libs/pull/937

Fixes ArcticaProject/nx-libs#935

Attributes GH PR #787: https://github.com/ArcticaProject/nx-libs/pull/787

NX does not support passing around FDs for local connections.

This will not cause any change in the resulting code as this variable
had been unset by default.

Fixes ArcticaProject/nx-libs#784

as it has been in the imake builds

Fixes ArcticaProject/nx-libs#783

Fixes ArcticaProject/nx-libs#781

Fixes ArcticaProject/nx-libs#780

Fixes ArcticaProject/nx-libs#779

Attributes GH PR #939: https://github.com/ArcticaProject/nx-libs/pull/939