The selection_mode property enables you to determine how many items in the list_box a user can select at one time and how the user can make multiple-selections. When the selection_mode property is set to selection_mode::multi_extended, pressing SHIFT and clicking the mouse or pressing SHIFT and one of the arrow keys (UP ARROW, DOWN ARROW, LEFT ARROW, and RIGHT ARROW) extends the selection from the previously selected item to the current item. Pressing CTRL and clicking the mouse selects or deselects an item in the list. When the property is set to selection_mode::multi_simple, a mouse click or pressing the SPACEBAR selects or deselects an item in the list.