How to insert fragment with behavior into main layout? Implementation I need to add BottomSheetBehavior to ToolboxSheetFragment that locate to activity_main.xml. I did it the follow: // activity_main.xml But in this case, ToolboxSheetFragment must to know, that behavior locate in parent view. class ToolboxSheetFragment : Fragment(R.layout.fragment_toolbox_sheet) { // ... override fun onViewCreated(view: View, savedInstanceState: Bundle?) { // ... behavior = BottomSheetBehavior.from(view.parent as View) } }...