For some reason it does not work in the menu directly, but I managed it using this:

<script runat="server">
 function GetPath() as string
    Return SkinPath & "test.gif"
 end function
</script>

<dnn:TREEVIEW runat="server" id="dnnTREEVIEW" level="root"  TreeIndentWidth="2"  ForceDownLevel="True" NodeCollapseImage="<%#GetPath%>" />

Timo,

1. I am apologies for syntax U describe is NOT allowed within attribute list of runat=server tag, because it IS SUPPORTED, sorry again

now to have complete this issue see what works for me:

<!-- workaround script for dnnTreeView -->
<script runat="server">
 String GetPath()
 {
    return SkinPath;
 }
</script>

...

  <div id="LeftPane" runat="server" class="TreeViewMenu_Body">
    <dnn:TREEVIEW runat="server" id="dnnTREEVIEW"
      level="root" 
...
      ForceDownLevel="True"
      NodeCollapseImage='<%# GetPath()+"minusBig.gif" %>'

my page lang is C#, so I turned your function into it. Please note that attribute NodeCollapseImage MUST have ' single quote enclosing' in this case.

Note: Image file name MUST be either append like example above or sent as param to function, but definitelly U CAN'T do something like:

NodeCollapseImage='<%# GetPath() %>minusBig.gif'

Despite to most horrible syntax I've ever seen, thanx for help and if anybody can set this thread as resolved please do it (I can't see button).

Thanx again

Adam