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By default, all changesets are highlighted. Starting from the version 2.3.0, you You can click a point to highlight where a changeset comes from, i.e. its ancestors. To have all changesets highlighted again, click anywhere outside points on the graph.
Starting from the version 2.3.0, it It's possible to collapse and expand the sidebar with Commit Graph. Click the button ( 
or 
) located to the left of Commit Graph.
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