Ninad, just to be sure you are aware of all the issues, here is a little overview.
When you do "normal" edit of data, relational data (not just foreign keys) is fetched. It can come from foreign keys (InnoDB, PBXT), or from phpMyAdmin's configuration storage, see libraries/relation.lib.php in PMA_getForeigners() and the "source" parameter.
Also, $cfg['ForeignKeyMaxLimit'] plays an important role. This is because we don't way to display a too big drop-down for the possible values. If these are more than this limit, a link to browse_foreigners.php is displayed, showing a distinct window with search capabilities.
There is also a "display field" that represents each row (for example, the key would be "id" and the display field would be "city name").
How do you plan to present relational data in the inline interface?