Global vs Workspace controls split can feel confusing

[jwunderl]

Describe the bug
My first action when testing keyboard controls was to open the hints, and start trying to use them; however, when you do that, only a few work. I first wanted to click L to try and download to see an immediate response, but nothing happened; then i tried w to select the workspace, but that also does not work. It sounds like current intention is ctrl+B -> 4 in that scenario to get back, but 'get back to my code' feels like a common action and that's a fairly dense interactoin.

To Reproduce
Steps to reproduce the behavior:

1. Go to blocks editor in narrator mode
2. control+/ to see keyboard shortcuts
3. try to do one of the actions in blocks workspace, because those are the ones that 'feel' most likely to want to be used / take up most of the screen
4. See error, the button event is captured in the iframe and does not do anything

[microbit-matt-hillsdon]

This is a tricky trade off. Making single letter shortcuts work in these sidedocs seems likely to cause conflict with screen reader shortcut use in reading documentation. Behaviour is as per last year's keyboard controls plugin in this respect.