walking a tree

i have a xml document like this:
<root>
<list name="foo">
  <object>
    <name>apple</name>
    <size>2</size>
    <id>1</id>
  </object>
  <object>
    <name>orange</name>
    <size>5</size>
    <id>2</id>
  </object>
  .....
</list>
<list name="connections">
  <connection>
   <inId>1</inId>
   <outId>2</outId>
  <connection>
 ....
</list>
<tree dataListName="foo" connectionListName="connections" >
  <display>
    <property field="name" />
    <property field="size" />
  </display>
</tree>
</root>

so in this case the apple would be connected to the orange =)
i want that for every node it displays the name and then the size
property..

now i would like to literaly create a tree out of this data.
i came up with some code.. however i always have issues with
loosing the context. especially concering the display with the
property part.

ciao!
florian