Working with nonvisual parts
Once you have laid out the user interface, you will need a simple model and connections between the user interface and the model.
The parts palette contains parts that can help you implement your application's logic. Unlike visual parts, nonvisual parts may only be added to the open area of the free-form surface.
For the To-Do List application, the items in the list need to be kept in the order the user added them. You need a part that is capable of maintaining a list (or collection) of objects in a particular order. The Ordered Collection part does just that.
Adding an Ordered Collection part
From the parts palette, select the Models category
, then select the Ordered Collection part
and add it to the free-form surface.
, then select the Ordered Collection part
and add it to the free-form surface.
Note:
If you try to add the nonvisual part over a visual part like a window, the mouse pointer changes to a "not allowed" symbol and will not let you add the part.
Last modified date: 06/18/2018