The multiSelectRectangle property (string) determines the rectangle event selection mode. When the rectangle selection mode is enabled it lets users select multiple scheduler events using drag and drop (while holding the Shift key).
See also Event Multi-Selecting in the documentation.
Note: This is a legacy property that has been replaced by rectangleSelectHandling and rectangleSelectMode properties.
"Disabled"
"Free" - enables free-hand selection
"Row" - limits the selection to a single row
"Disabled"
dp.multiSelectRectangle = "Free";