Tree View navigation collapsed image URL

Question

I setup my master page in SharePoint 2010 with the Tree View navigation as:

<Sharepoint:SPTreeView
id="WebTreeViewV4"
runat="server"
ShowLines="false"
DataSourceId="TreeViewDataSourceV4"
ExpandDepth="0"
SelectedNodeStyle-CssClass="ms-tvselected"
NodeStyle-CssClass="ms-navitem"
SkipLinkText=""
NodeIndent="12"
ExpandImageUrl="/_layouts/images/tvplus.gif"
CollapseImageUrl="/_layouts/images/tvminus.gif" 
NoExpandImageUrl="/_layouts/images/tvblank.gif">
</Sharepoint:SPTreeView>

However, when I view any page with content in the Tree View, it uses "/_layouts/images/MDNCollapsed.png" instead of "/_layouts/images/tvminus.gif" as I specified. What's going on?

Answer 1

According to Microsoft, any site that you pull over from 2007 to 2010 will have this behavior, but any site that you create in 2010 will use the correct icons.