- Top-level GFM tables render as an editable widget: click a cell to
edit its Markdown source, Tab/Enter/arrows to navigate, toolbar to
insert/delete rows and columns or switch to source
- Structural table edits are isolated undo steps; focus is restored
after the widget is rebuilt
- Clicking an image moves the cursor to its syntax to reveal the source
- Renderer escapes raw HTML and filters dangerous URL schemes by default