Unfortunately we cannot rename NX_CUT_BUFFER_SERVER, too, without
breaking compatibility because this one is used to signal nomachine's
nxclient after the splash screen is gone (see Splash.c, Window.c and
ArticaProject/nx-libs#838)

the MakeAtom call previously used is as good as using a variable but
with the variable it is a) easier to read/understand and b) consistent
with the other client* variables.

Using this macro makes the code more readable

We do not need to loop over all selections. We have a helper for that.

It makes sense to measure time and set the initialized flag right at
the start.

The new code effectively does the same the old one did. But if we
change the number of selections the new code will still work correctly
while the old one would not.

On reconnect claim the selection ownership if one of nxagent's clients
is a selection owner. The code for this was already there but could
not work because the lastSelectionOwner array was always dropped at
the beginning of nxagentInitClipboard.

Place the allocation directly before the check for success. Use the
same order for server and client atoms.

Always report the same list of available targets to internal and
external requests.

The code also worked with pWindow being NULL but it did some
unnecessary stuff.

By splitting it up we can print appropriate debug messages. More
important: The code tried to handle the special targets for all other
cases where it should only deny the request.

We had comparisions for >5000 and <5000, but =5000 was not explicitly
handled. In that case the code took an unexpected path.

The prototype for nxagentGetClipboardWindow has been changed in
63320437 but the changes have not made
it into NXproperty.c...

and add debugging information around its checks.

expect an index instead of a pointer

All calls referenced lastSelectionOwner so let the function directly
use it and only pass the required index.

Attributes GH PR #884: https://github.com/ArcticaProject/nx-libs/pull/884

no more hardcoded string length

no more hardcoded string length

no more hardcoded string length