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Clicking the pin icon will switch its state from pinned to unpinned and vice versa:
When unpinned, clicking the icon will switch the pane to expanded, pinned state (see States above).
When pinned, clicking the icon will switch the pane to expanded, unpinned state (see States above).
 | When the pane is unpinned   |
When the pane is pinned  |
The Collapse/Expand Area
Hovering the collapse/expand area switches it to hover state.
When the pane is expanded, clicking the area switches it to the collapsed state.
When the pane is collapsed, clicking the area switches it to the expanded state.
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