Constraining what activities can be dropped on a custom activity designer in Windows Workflow Foundation 4

When designing a custom activity that can be used as a container for other activities, you may want to restrict the activity user to a certain set of activities. If the custom activity can only accept a single type, this can be implemented quite simply by setting the WorkflowItemPresenter.AllowedItemType or WorkflowItemsPresenter.AllowedItemType property. In this example,…