Olivero Doesn't Explain Menu Behavior When Migrating From Other Themes

Problem/Motivation

When migrating to Olivero from another theme that has a large main menu, the site comes up under Olivero displaying the menu solely in the mobile version with no explanation for why this is happening. Having gone through this scenario myself as a highly seasoned Drupal developer who simply happened to be new to Olivero, it was extremely frustrating trying to figure out how to get the standard desktop style menu to display on my site. Only by installing a fresh copy of Drupal and building up a menu from scratch did I finally figure out what Olivero was doing.

Steps to reproduce

Create a site under something like Bartik with a menu consisting of ten or more top-level items. Switch the site to Olivero. On going to the front page, the main menu shows in desktop mode for a brief moment and then it is wiped out and replaced with the mobile menu. No explanation is given anywhere during the theme activation process or on any of the Olivero related settings pages that this is going to happen or why. The existing "Enable mobile menu at all widths" setting adds to the confusion, as one is led to think that setting is stuck on, even though it is not checked.

Proposed resolution

I see two possible remedies, and it might even make sense to do both:

1. Add a documentation status message when Olivero is enabled that warns the user that large menus may display in mobile mode, and to fix this the user needs to pare down their menu to fewer top-level menu items.
2. Add another settings checkbox item for "Never show mobile menu on desktop views." that would disable mobile menu for all window widths above something like standard vertical table width. This setting would then be on by default, ensuring that when migrating a site to Olivero, the main menu will show fully as expected, even if it wraps in an ugly way. The user can then decide how to adjust the menu to not be so ugly. If the user wants to enable the current automatic switching to the mobile menu even on desktop widths, they can go into settings and disable the new setting.

Either way, the experience for users migrating existing sites into Olivero needs to be improved, as I can easily see less experienced users throwing in the towel all to quickly and giving up on Olivero.

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet