I just did a HEL-NRT trip on a 787 with the electronic window tint system. The westbound flight is a 9h daytime flight and most people slept after the meal but one person kept their window in clear mode and flooded the cabin with light (especially so since we flew so far north and the sun was low in the sky for most of the flight).

On BA they centrally control the window tinting system and people in the window seats can only choose from the two darkest settings on long daytime flights like this, the window won't go any clearer than that regardless of pressing the buttons.

Do JAL not do this? What do people think of the BA method ? That those in the window seat should be allowed some light or the settings are locked and cabin kept dark for the majority of passengers?