Code review comment for lp://staging/~macslow/qtmir/fix-1475678

> void MirSurfaceManager::displayOff()
> void MirSurfaceManager::displayOn()
>
> I disapprove of this design. A surface manager should not care about display
> state. It's the shell's decision if a client surface should be marked
> invisible when the display is off.
>
> Also this throws away any visibility state that the shell may have set on
> surfaces.
>
> A remote desktop would be an example where we don't care about the actual
> display state.

displayOn()/displayOff() are just temp. methods for quicker testing of the correct working of the visible-flag propagation. They will not stay... it's a WIP-branch after all :)