Add a setting to somehow designate a point within the layer stack where the baseline grid would appear. The desire is to have the grid visible in front of a background layer but behind everything above that. Perhaps in Preferences->Grids where there is currently a "Grids in Back" checkbox, there could be an additional checkbox of "Except lowest layer" or "Except lowest __ layers" or something. Alternatively, the setting could be in Layer Options, something like "Show Grids in front of this layer". You get the idea.