By default, the AllowCreateElement property is exLeftClick + exDblClick, which means that a double click on the surface will create new elements ( you can double-click and drag to create a custom-sized element ). The AllowCreateElement property specifies the combination of keys that allows the user to create objects on the surface. Set the AllowCreateElement property on exDisallow to prevent creating new elements at runtime. Use the Background(exCreateObjectColor) property to specify color or visual appearance of the creation rectangle when the user creates a new object. The CreateElement event occurs when the user creates the element on the surface. The control fires the LayoutStartChanging(exCreateElement) / LayoutEndChanging(exCreateElement) event when the user creates a new element on the surface. 

The Add method adds programmatically a new element on the surface.

The order of the events when the user creates the element at runtime is:

• LayoutStartChanging(exCreateElement), the user clicks on the surface
• AddElement, adds the new element to the Elements collection
• CreateElement, the user ends creating the object
• LayoutEndChanging(exCreateElement), the user un-clicks the surface

The following screen shot shows the creating rectangle, for elements: