gp530-qt_wop.tar.xz, 3726728 bytes, 2019-03-08, md5 8f74a955ca9821cbd5a73e33fe232966,
gnuplot 5.3 (development version) package prepared by gcc-7.4.0 linked with Qt without patch (64 bit)
(Commit [3c0ac5])

gp530-qt-wp.tar.xz, 3726892 bytes, 2019-03-08, md5 d468057c6eebd8f6c2a34a6368b57f1d,
gnuplot 5.3 (development version) package prepared by gcc-7.4.0 linked with Qt with patch (64 bit)
(Commit [3c0ac5])

cygQt5Network-5-gp.dll, 1525248 bytes, 2019-03-08, md5 7d2802f7284da8f461fe7db4655bf8d3,
Patched cygQt5Network-5.dll. Place it to /usr/bin(64 bit)
(Commit [3c0ac5])

Note :
Install gnuplot 5.2.6 first using the cygwin setup.
Then almost required runtime libraries are installed.

Install wxWidgets3.0, GTK3, qt5(Qt5Core and Qt5Svg) runtime
libraries and mesa and dbus using the cygwin setup.

Extract this package.
Copy "opt" directory into Cygwin directory, e.g. /opt

Place cygQt5Network-5-gp.dll at /usr/bin

set environmental variables and alias in the ~/.bashrc like

 export DISPLAY=:0.0
 export XDG_RUNTIME_DIR='/tmp/runtime-(user name)'
 export NO_AT_BRIDGE=1
 export LIBGL_ALWAYS_INDIRECT=1

set Cygserver (for qt terminal.)
  Right click terminal launcher and run as administrator and execute below
  $ cygserver-config
  /etc/cygserver.conf 
  is produced and then execute 
  $ cygrunsrv -S cygserver
  Then cygserver service is registered to registry.