Use of PtToolbarGroup

I’d like to use a PtToolbarGroup, with several PtToolbar inside and to display only one PtToolbar, depending of the context of my application.
For example, widget tree should be:
PtToolbarGroup
PtToolbarGeneral
PtButtonAccessToolbar1 //Access to toolbar1
PtButtonAccessToolbar2 //Access to toolbar2
PtToolbar1
PtButton11
PtButton12
PtButtonReturnToolbarGeneral //Return to toolbarGeneral
PtToolbar2
PtButton21
PtButton22
PtButtonReturnToolbarGeneral //Return to toolbarGeneral

I try to set PT_ARG_POS to negative value for the 2 toolbars I don’t want to see, depending on the context, but it doesn’t work !

Any idea of solution ?

Thx !