When you work with the instructions and the arrows, you may need to
move, delete or cut/copy/paste some objects. Before any operation you have
to select the objects you want. The graph editor supports multiple selection
that can be done by tracking a rectangle with the mouse - see the figure
below
Selecting multiple objects
When you select more instructions, only the arrows between them are
selected. You can deselect on object by clicking it with CTRL key or SHIFT
key pressed down.