Hi Chanaka,
I've found a bug in master and after bisecting it looks like you've introduced it.
39d37fafcce29160c4dfe6ef7696de19bebb1d18 is the first bad commit
To reproduce:
* Enable configuration storage * Activate tracking on any table with default options * Go back to the database in which the table in question is * Select the tracking tab * Click "Drop" near the tracking entry you created * You will get an internal server error
From my error.log:
roccivic@gentile-desktop:~/www/pma$ tail -n 1 /var/log/apache2/error.log [Wed Aug 01 19:10:31 2012] [error] [client 127.0.0.1] PHP Fatal error: Call to undefined function PMA_query_as_controluser() in /home/roccivic/www/pma/libraries/Tracker.class.php on line 374, referer: http://localhost/pma/db_tracking.php?db=test3&token=f01096a0fa6885a13fcc...
Bye, Rouslan