ListView and GridView have an identically-sized space for every item in the list, even if the item is collapsed. You'll have to actually remove the item from the list in order to get rid of the space.
Matt Small - Microsoft Escalation Engineer - Forum Moderator
If my reply answers your question, please mark this post as answered.
NOTE: If I ask for code, please provide something that I can drop directly into a project and run (including XAML), or an actual application project. I'm trying to help a lot of people, so I don't have time to figure out weird snippets with undefined
objects and unknown namespaces.