The Collection Editor dialog box in the Silverlight Designer for Visual Studio is used to add items to and remove items from a collection property in the Properties window. The Collection Editor is available for any property in the Properties windows that has an ellipsis button. For example, when you add items to the RowDefinitions property of a Grid control through the Properties window, you use the Collection Editor.The following image shows the Collection Editor dialog box.
Collection Editor Dialog Box
Enables you to select the type of item to add to the collection.
Enables you to add a new item to the collection. The new item is added to the bottom of the list and given a default name. You can change the name and other properties in the Properties grid.
Moves the selected item up in the collection.
Moves the selected item down in the collection.
Removes the selected item from the collection.
Displays the properties you can edit for the currently selected item. The specific properties you can edit depend on what collection you are editing. The Properties grid works much like the Properties window; you can search and sort the collection properties. Some features, such as Events, are not available.
In some cases, the properties of the current item contain additional collections. If so, you can open a nested version of the Collection Editor for that collection.