Behaviour History Map

1. node background colour: active tab - blue; favourite/starred node - yellow *
2. node border: dashed for unopened tabs; solid for opened tabs *
3. Different nodes have the same URL: existing node(s) with the same URL 'flashes' when the new node is added.
4. auto panning/zooming to keep the active tab in focus *
   1. Need buttons for zoom in and out
   2. Semantic zoom instead of geometric zoom:
      1. the amount of information showed for node reduces as user zooms out; not just smaller size.
      2. First reduce the size of nodes without highlight or annotation. When all such nodes are reduced to a dot,
      3. Reduce the size of node with highlight or annotation, but not only smaller not to a dot.
   3. Zoom first, and then pan when it is not possible to fit in everything even after zooming out.
5. node label disambiguation: compare the node label with its parent's and replace the duplicate part with '...'
6. 'Note view': a history map view that shows only the highlights and annotations; all other nodes are reduced to minimal (a dot).
7. This is not needed if the 'auto zoom/pan' works.
8. page screenshot/thumbnail*: shows a screenshot/thumbnail of a webpage when mouse over a node
9. Closed tab: greyed out nodes or dashed borders.
10. last a few opened tab:
    1. boldness of the font: the more recent, the bolder
    2. Only the three most recent nodes; so there is enough visual difference in boldness.

Item marked with a * means at least some code is available in another branch: the 'master' branch or the 'rebuild-old'.