A shell script that uses Zenity to show current date and time (read more at https://bit.ly/showDateTime).

showDateTime.sh

#!/bin/bash

# COPYRIGHT: That Mahesh RS (https://sites.google.com/site/thatmaheshrs)
# 
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# 
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# 
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
# 
# ---- README ----
# install this script in /usr/local/bin
# then chmod +x this script
# then you could add a keyboard shortcut to invoke this script

WEEKDAY=`date +"%A"`
MONTH=`date +"%B"`
DAYOFMONTH=`date +"%d"`
YEAR=`date +"%Y"`
DATE=`date +"%F"`
TIME=`date +"%I:%M %p %Z"`

SHOWDATE="${MONTH} ${DAYOFMONTH}, ${YEAR}"

DATE_TIME_TO_SHOW="
<span font='22' color='blue'><tt>Day : </tt></span><span font='32' color='brown'>$WEEKDAY\n</span>
<span font='22' color='blue'><tt>Date: </tt></span><span font='32' color='darkgreen'>$SHOWDATE\n</span>
<span font='22' color='blue'><tt>Time: </tt></span><span font='32' color='green'>$TIME\n\n</span>
<span font='10' color='blue'><i>Hit 'ESC' to close this window or wait till progress bar is full.</i></span>"


PROGRESS_COUNT=0
PROGRESS_COUNT_MAX=110 # in %
PROGRESS_COUNT_INCREMENT=15 # i.e. jump up 15% at a time

while [ ${PROGRESS_COUNT} -lt ${PROGRESS_COUNT_MAX} ]
do
  echo ${PROGRESS_COUNT}
  sleep 1
  PROGRESS_COUNT=`expr ${PROGRESS_COUNT} + ${PROGRESS_COUNT_INCREMENT}`
done | zenity --progress --auto-close --no-cancel --title="Date and Time" --text="${DATE_TIME_TO_SHOW}"

Code cleanup:

1. Updated the script to remove some cruft.
2. Also added some vars in place of magic numbers.

HTH!