Relative URL in Sharepoint is incorrectly resolved

Today I had a problem with the TreeView WebControl. I wanted to set the NavigateUrl to a relative url in Sharepoint in one of my webparts (I allow user configuration of this property so this must be resolved correctly).

When I set the NavigateUrl to "test.aspx" it's resolved to: "_catalogs/masterpage/test.aspx" which probably has something to do with the fact that the webpart manager containing my webparts is declared in the masterpage.

The solution was simple: Use Page.ResolveUrl before setting the url. This correctly resolves the relative url before it's set to the TreeView:

string relativeUrl = "test.aspx";
treeNode.NavigateUrl = Page.ResolveUrl(relativeUrl);