Allow `currentIndex` to be null in SidebarItems

[Vorkytaka]

Feature Request:

The SidebarItems widget in the macos_ui package currently requires currentIndex to always be a non-null value between 0 and the total item count, forcing a selection at all times.

Use Case:

When implementing a search function with dynamically updated items, it may be preferable to have no item selected by default (for example, when selected item is out of search). Allowing currentIndex to be null would better reflect an unselected state during such updates.

Proposed Solution:

1. Enable currentIndex to accept null.
2. Adjust widget logic to handle the null state so no item is highlighted.

[Adrian-Samoticha]

Are there any native applications that use the sidebar as a search result list? I believe native apps typically have a search bar that displays search results underneath itself (and I’m quite certain that we provide widgets that implement that as well).

[Vorkytaka]

While searching for examples, I realized that in addition to the panel under the search bar, there could be a replacement of all content in the sidebar.

For example, in System Settings, when searching, the entire Sidebar starts to change.

I realized that nothing prevents me from implementing something similar with macos_ui in the current form, although I will have to do some tricks.

I still think that the ability to not specify selectedIndex can be useful, but if you disagree you can close the issue.
Thanks.

[Adrian-Samoticha]

You’re right. The sidebar in the settings app does also allow the user to navigate it using the arrow keys (which works even without any search input). I’m not macos_ui even supports that atm, but it’d be crucial to support when using the sidebar as a search results list.

I’ll assign myself to this issue, though I’m not sure when I’ll find the time to tend to it at the moment.