Using the keyboard
There are two basic directions of node movement, left⁄right and up⁄down. Shift+Left⁄Right moves the node up or down a level in the tree hierarchy, while Shift+Up⁄Down moves the node up or down in relation to its siblings in the same subtree. Combined, the two groups of commands enable you to move a node anywhere up or down the tree just using the keyboard.
Try this out in Tree1.tpd by making node A2 a child of node B. Start by selecting (focusing on) node A2.
Press Shift+Up to move A2 above A1.
Pressing Shift+Up again won't do anything because A2 is already at the top of its subtree, but pressing Shift+Left will move it up a level in the hierarchy to become a sibling of node A.
Similarly, press Shift+Down to make it change places with node B.
Last, press Shift+Right to move it down node B's hierarchy, i.e., make it a child node of B. Note that this causes B's subtree to open.
(It should be pointed out here that this has no effect on B1's subtree, which happened to have been closed beforehand.)
Remember that if the node has child nodes, the whole subtree is moved with it.