Left/right navigation doesn't quite work correctly with subcategories

[BenHenning]

See this video from issue #149:

Screen.recording.2025-02-24.4.34.35.PM.webm

(Note that this includes changes from #225)

Using left/right navigation on a parent category doesn't allow its blocks to be navigated to as 'right' either expands the parent category or navigates to its children.

This is actually a bit tricky because 'down' and 'right' can be ambiguous when it comes to nested categories. 'Down' presumably means to navigate to the next available category/subcategory (which means skipping children if a parent is currently collapsed), whereas 'right' can mean either 'expand', 'navigate to next', or 'navigate to blocks'. Two (of likely many) possible solutions may be to:

• Always expand subcategories when keyboard navigation is enabled to simplify the navigation experience (though this could become unwieldy for very large amounts of nesting).
• Have 'right' mean to expand the subcategory first and navigate to the category's blocks second, though this will need to have some sort of readout feedback and it's potentially confusing/frustrating to require two actions to navigate to a category's blocks.

[rachel-fenichel]

What about using up/down to move between categories in the toolbox, left/right to go into the flyout, and Enter on a category to toggle expansion of its subcategories?

[rachel-fenichel]

@microbit-matt-hillsdon Are you okay with my proposal above?

[BenHenning]

What about using up/down to move between categories in the toolbox, left/right to go into the flyout, and Enter on a category to toggle expansion of its subcategories?

Created #552 to demonstrate this proposal. If it's agreeable, I can go ahead and finish that up & send it out.

[rachel-fenichel]

Matt says "This is behaviour that MakeCode implements separately so we don't need anything here with any urgency. MakeCode has systematic "more" subcategories in its toolbox that are autoexpanded/collapsed by up/down navigation. This behaviour predated our work on keyboard nav and we've not changed it."

So I'm moving this into post launch so we can apply the fix and some tests at the same time.