When a person moves through a document, for e.g. while doing a final proofread of a long post, either scrolling and using a mouse, or using keyboard navigation (up and down arrow keys, page and page down), how should the toolbars behave? Under what conditions should they become visible to reduce visual distraction?

Contextual toolbars identified so far ( #190 and #16 ):

1. Block move controls (up and down arrows)
2. Block type selector/transformer
3. Block action toolbar (align, delete, clone?, ...)
4. Selection (text, image, etc) toolbar

Possible block states:

1. Normal block
2. Selected block
3. Cursor in block (?)
4. Hovering on block
5. Content within block selected
6. Empty (placeholder) block

Relevant discussion from #core-editor today