When a command is active, you often need to select objects in order to proceed. You can add a single object or multiple objects to your selection set.
You can also select objects before you activate some commands, such as ERASE, MOVE, ROTATE, or MIRROR.
When using the selection box, click and hold in the Drawing Area and then release to establish the selection box. If you specify the corners from left to right (called window selection), all objects inside the selection area are added to your selection set. If you specify the corners from right to left (called crossing selection), all objects inside or crossing the box are added to the selection set.
Add or subtract objects to or from a selection set by selecting the object(s) while holding Shift.