You can put code in the TreView Expand event to capture node expansion.

*** ActiveX Control Event ***
LPARAMETERS loNode
lcStr = ''
lcTitle = 'Child Nodes for ' + loNode.Text
loChildNode = loNode.Child
DO WHILE VARTYPE( loChildNode ) = 'O'
  lcStr = lcStr + loChildNode.Text + CHR( 13 ) + CHR( 10 )
  loChildNode = loChildNode.Next
ENDDO
MESSAGEBOX( lcStr, 64, lcTitle  )

>Thanks Doru,
>It worked, but isn't it hard to keep track of all nodes that are expanded? This because your suggestion gives you the answer of all nodes, which are expanded, and if you have plenty of nodes and just want to know which node was expanded last, it would be more convenient if there is any method to get this answer more directly.