Mac Book Pro has a cool feature: the keyboard keys illuminate in the darkness. Therefore it is easy to work with the computer in total darkness. Apple seems to be so excited about this feature that by default two keys on the keyboard are dedicated to controlling this backlight:
There are also settings in System Preferences that totally disable this feature. If you let the computer to automatically adjust the backlight based on the current environment conditions, the manual adjustment controls are disabled (for obvious reasons!). Therefore when you try to manually control the keyboard backlight when the automatic settings are in effect, you only see this:
This happened to me since a few days ago and I had no clue why all of a sudden I am not able to change the keyboard backlight. A computer restart didn’t help so I started googling. Apparently it is a very common issue and confused many users: look here, here, here and here. There’s more! Google it.
Anyway, the solution is really simple once you know it (but very hard when you don’t know it). Just disable the automatic backlight adjustment and the manual adjustment buttons work:
This is a feedback issue. When the automatic adjustment is preventing manual settings, user should be notified about the reason. A simple “forbidden” icon doesn’t do the job. Having textual description and even a shortcut link to the keyboard settings might be more helpful.
Another solution would be to allow the user override the automatic settings just by pressing the manual controls. The automatic settings can be relative instead of abstract. That is: the current automatic backlight can be adjusted based on user settings. For example in a light environment, less backlight is needed, so the backlight can be 10% of what the user has manually chosen. Or in a dark environment, more backlight is needed so it can be 100% of the light that user has manually chosen.