I should say, as often with VFP, it depends.
If you're using the mousedown event in conjunction with hittest to determine if a node has to be selected or not, it's fairly possible.
some piece of code in mousedown could be like this one :

If m.Button = 1
loNode = THIS.HitTest(x , y )
If not isnull(loNode)
*-- here, you can add some conditions of yours
If myConditionisTrue
m.loNode.Selected = .T.
Endif
m.loNode.Expanded = .T.
Endif
Endif