Editor Modes: Navigation in Select Mode doesn't work smoothly with nested blocks

[gziolo]

Describe the bug
Upon entering "Navigation" mode from the nested block, you got stuck in the context of the parent block. You can't use arrow up/down keys to navigate to the parent block. In addition, if there is only one child block, then those keys don't work at all and sometimes the focus gets lost. In effect, you can't enter "Edit" mode anymore with the keyboard.

The same issues exist when tabbing after "Navigation" mode gets enabled for the nested block. The behavior is slightly different. Pressing Tab moves the focus to the Publish Panel. Pressing Shift + Tab moves the focus to the block controls which shouldn't show up in this mode.

Expected behavior
Both arrow up/down keys and tabbing works properly and respects both children and parent blocks.

Screenshots

Desktop (please complete the following information):

• OS: macOS
• Browser Safari
• Version 13

Additional context
Gutenberg 7.0 - the latest master.

[gziolo]

I tested again, and it seems to work as expected now. Arrow keys navigation is locked down to it's immediate parent, but tabbing allows to go to the pre/next block regardless of the context.