I would modify the menu interface in ED9. How can I add buttons and functionalities to the main menu? What are the files to edit? I tried to change the files in *\Documents\Enterprise Dynamics 9\Apps but nothing happened.
In Enterprise Dynamics 9 the Main menu is created by the function Menu_CreateMainMenu. This function is defined on the Menu atom that can be found in the systems group of the Library. On the functions page of the atom editor you can see all the function defined on the Menu atom.
The function is called when the library is loaded into your model. If you have the Developer tools package installed you can see where the function call is made: Switch to the Developer page in the Main menu and click Create Package, a window appears. Click Load to Enterprise Dynamics.lbrx. Note that the Init function code of this package is the call to create the Main library.
Note that the developers tool package adds the Developer page to the Main menu. See the function: DeveloperTools_Init.
With Enterprise Dynamics 9 you can create your own packages, determining which atoms to load but as you can see also add other functionality and make changes or additions to menu's. To Create packages use the Create packages button on the developer page of the main library. To manage which package are loaded use the manage packages button on the Tools page of the Main menu. Note that doing this will have effect on the files in the folder \Documents\Enterprise Dynamics 9\Libs. See also the Help files of the developer tools.