after i populate my grid (in virtual mode) with a dataviwe, is it possible to add rows to a certain node?
In this case you can use VirtualMode_GetCount and VirtualMode_InitNewNode events to provide additional nodes of certain node.
Firstly you should provide your own node that provides
** is it possible to show rows under a node but without the root lines?
(it should look like an ordinary rows in a table)
You can set ShowLines or ShowOutline properties of HierachyColumn or TreeViewColumn to do not show root lines.