[merlight]

Another edit: I got it wrong

Untested, not sure it does what you want:

local g_tlwHiddenInMainUI = true
 
-- then in your fragment construction:
 
fragment:RegisterCallback("StateChange", function(oldState, newState)
  if newState == SCENE_FRAGMENT_SHOWING then
    tlw:SetHidden(g_tlwHiddenInMainUI)
  elseif newState == SCENE_FRAGMENT_HIDDEN then
    g_tlwHiddenInMainUI = tlw:IsHidden()
    tlw:SetHidden(true)
  end
end)