Tap to select an object: tap on an existing object to select it when there is no command running.
Window-select: click or drag from left to right in the drawing area, you can select objects that
completely located in the rectangle area.
Crossing: click or drag from right to left in the drawing area, you can select objects partly
located in the rectangular area.
Selection set: a group of selected objects. Object can be selected by clicking or dragging to
define a rectangle area.
Deselect: tap on a selected object to deselect.