Advanced menu (main,context) configuration like order, aligment, grouping and behaviour
If using some additional plugin with own project tabs, standard redmine theming wraps ugly. Grouping things and making this configurable independent of plugins default would be best. So However plugins register default, a admin can configure how hooked in menu shall be shown.
Besides general aligment (left vertical like chilis theme) or horizontal like redmine standard) and admin shall be able to choose the order (top-down or left right) how the menu items are shown, and at least if they are shown at all (e.g no New issue menu).
Furthermore such a 1 level menu can get soon very long if you have "some" plugins. SO a grouping feature (2nd level menue) shall be configurable) . First level menue what juts be a free configruable label and below a admin can drop core/plugins menu items as he wants.
See also left aligend main for chili project default theme and grouping feature.