public bool ForceSelectionModifierKey { get; set; }
true if the user can draw the selection object only when one of its key modifiers is pressed; otherwise, false. The default value is false.
ForceSelectionModifierKey and SelectionModifierKey are used when the selection automation object (SelectObjectId is present). This object allows the user to select multiple annotation objects by clicking anywhere on the container outside the boundaries of any of the other objects and drawing a rubber band.
When the value of ForceSelectionModifierKey is false (the default), then SelectionModifierKey is not used and the user can start drawing the selection rubber band using the mouse (or touch) only.
When the value of ForceSelectionModifierKey is true, then the user can only start drawing the selection rubber band if the modifier specified is also pressed.
ForceSelectionModifierKey is only used if the current platform supports a physical keyboard.