BuddyPress.org

Is the eshop plugin a buddypress plugin really? If it is designed to work with WordPress, it does not hook into the menu functions etc that BuddyPress uses. Contact the author of that plugin and talk to him/her about it.

What do you mean by “menus and new tabs”? If you create a plugin, you can add custom menu items related to your plugin through various hooks (see the Skeleton Component for examples), but there are no built-in drag’n’drop functions for it.