How to retrieve Gadget Handle ?

[G-Rom]

Hi, i need to have access to the os handle of any gadget ( in windows GadgetID() return a os handle )

in linux i try this :

PB_CONTAINER = ContainerGadget(#PB_Any,10,10,100,100,#PB_Container_Single)

*Widget.GtkWidget = GadgetID(PB_CONTAINER)
*WinObj.GdkWindowObject = *Widget\window
*GdkDrawable.GdkDrawableImplX11 = *WinObj\impl

*GdkDrawable\xid <-- HANDLE ?

But when i rendering my sfml context inside the handle , whole window are used , not just the gadget.
this is the correct way to have the os handle ?