Go to /path/to/phpmyadmin/config.inc.php (or something similar)

Change these settings:

$cfg['Servers'][$i]['controluser'] = 'pma';
$cfg['Servers'][$i]['controlpass'] = 'yourpass';

(don't forget to give user pma a password otherweise people can easily see your table design info) 

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Now change the names of the databases like beneath (note that table names are case sensitive, use lower pma):

$cfg['Servers'][$i]['pmadb'] = 'phpmyadmin';
$cfg['Servers'][$i]['bookmarktable'] = 'pma_bookmark';
$cfg['Servers'][$i]['relation'] = 'pma_relation';
$cfg['Servers'][$i]['table_info'] = 'pma_table_info';
$cfg['Servers'][$i]['table_coords'] = 'pma_table_coords';
$cfg['Servers'][$i]['pdf_pages'] = 'pma_pdf_pages';
$cfg['Servers'][$i]['column_info'] = 'pma_column_info';
$cfg['Servers'][$i]['history'] = 'pma_history';
$cfg['Servers'][$i]['designer_coords'] = 'pma_designer_coords';

/////////////////////////////////////////////////////////////////////////

As final you must run a SQL script that you can find in:

/path/to/phpmyadmin/scripts/create_tables_mysql_4_1_2+.sql
simply execute this sql with the phpmyadmin import function and it will create phpmyadmin database and tables defined above.

DESIGNER MODE IS NOW AVAILABLE