If you want to do an edit operation such as Copy, Cut, Delete for
few nodes you must select these nodes.
Main rules of selecting:
1. If you select a node then all its sub nodes are selected.
2. You can select few nodes at a time, but they must be nodes of the same level.
You may select nodes use a mouse or keyboard.
Use a mouse in Program Tree Editor like in Windows Explorer.
More action for selecting is available
if you use the keyboard and
advanced caret movement
All keyboard actions.
Shift + Home
Shift + End
Shift + Up
Shift + Down
Select / Unselect this node
Select / Unselect all nodes at level
Select nodes to first at line
Select nodes to last at line
Select nodes to previous node
Select nodes to next node