用vb自带的方法就这样:
Private Sub TreeView1_MouseMove(Button As Integer, Shift As Integer, x As Single, y As Single)
Dim mnode As node
Set mnode = Me.TreeView1.HitTest(x, y)
If ObjPtr(mnode) = 0 Then
Me.TreeView1.ToolTipText = ""
Else
Me.TreeView1.ToolTipText = mnode.Text
End If
End Sub