After showing docked block using keyboard navigation, tab order does not jump to block

When tabbing through the page, when a docked block is reached, after expanding a docked block the user may expect to be able to tab immediately to the block. Instead, the tab order is unchanged and the user must tab through all lower docked blocks and the "remove all" button before reaching the block they have just shown.

Replication steps:

1. Log in as any user
2. Navigate to a course
3. Dock the Navigation and Administration blocks
4. Using the tab key on the keyboard, navigate to the topmost docked block.
5. Show the docked block by clicking enter, space or right-arrow.
6. Click tab again.

Expected result: You start navigating through the block.

Actual result: You have to tab through other docked blocks and the "remove all" button before arriving at the block you just showed.