I still have the same problem with Mantis 1.0.7.

with $g_main_menu_custom_options = array ( array( "Manage project", ADMINISTRATOR, 'manage_proj_page.php' ) );

"Manage project" only appears when Project Access Level of the user is ADMINISTRATOR. But it doesn't appear if the Access Level of the user is ADMINISTRATOR for a specific project, when this project is selected.

Am I clear ? ;-)

In core/html_api.php: prepare_custom_menu_options()

Replace:
access_has_global_level

With:
access_has_project_level

Let me know if this fixes the problem.

Thanks vboctor !

It's ok, now :-)