TreeView - detect node position change

Question

I have TreeView:

Group01
 - PackageP1
    - ComponentC1
    - ComponentC2
Group02
 - PackageP2
    - ComponentC3
    - ComponentC4
Group03
 - PackageP3
    - ComponentC5
    - ComponentC6

The position of the nodes of this treeview can be changed via Drag&Drop, keyboard hotkey and separate Up/Down buttons. How to react when node will change it's position on the TreeView? I didn't find anything which might be Event OnNodeIndexChange.