Drag a text selection over multiple nodes to break them off into a new branch.
The nodes that will be placed under the new branch will be shaded gray while selecting.
To discard the selection without creating a new node, simply drag to a point outside the tree.
Double click a node to undo a branch, collapsing its children into its place.
You cannot collapse the root node.
Click on a node to edit its value.
You cannot edit the terminal nodes' values.