Specify whether the action shows a shape selection window.
property UserInterface: Boolean;
If False: the action simple inserts a shape and assigns its properties.
If True: the action displays a shape selection window, then inserts the chosen shape. Some shape properties are taken from the shape selection window, others are taken from the action properties.
The shape selection window is the same as the window displayed by ShowInsertDialog method. If action was initiated by a button, the window is displayed below this button (for old version of Delphi, use CallerControl), otherwise it is displayed at the position of the mouse pointer.