That is bug 1314678, which has also been covered in the spec since April 2013: "If it is checked and you adjust the brightness manually, the function that determines the automatic brightness should be adjusted such that, in future, the current ambient light value would result in your just-chosen brightness being chosen automatically." I even drew a bunch of graphs to illustrate how it should work.
If graphs aren't your style, here's an example in text: If the ambient brightness in your office is X, which results in an automatic brightness of Y, then the brightness slider should show Y (this bug). If you then move the slider to Z, the brightness should change to Z (bug 1314678). If you then go out into the street, the brightness should adjust accordingly, because automatic brightness is still on, and the slider should reflect that new brightness (this bug). If you then go back into your office, the brightness should change to Z, because that's the brightness you last chose for the office's level of ambient light (bug 1314678). ** Changed in: ubuntu-ux Status: Confirmed => Fix Committed -- You received this bug notification because you are a member of Unity API bugs, which is subscribed to indicator-power. https://bugs.launchpad.net/bugs/1370791 Title: [system-settings] When brightness is set to automatic, the slider doesn't show current value Status in the base for Ubuntu mobile products: Confirmed Status in The Power Indicator: Confirmed Status in Ubuntu UX bugs: Fix Committed Status in indicator-power package in Ubuntu: Confirmed Status in ubuntu-system-settings package in Ubuntu: Confirmed Bug description: On the brightness page, there is a slider to set brightness and a checkbox to set it automatically. When I select the automatic brightness, I was expecting the slider to show the current brightness level. Instead, it just keeps the old value manually set. I find this a little confusing: I have a slider whose value I can change, but will do nothing while the checkbox is marked, and the value it shows is different from the current brightness of the screen. <https://wiki.ubuntu.com/BrightnessAndDisplays#Phone>: "Because users have different preferences, the function should also be user- adjustable. This should be achieved by altering the display brightness manually while 'Adjust automatically' is checked." To manage notifications about this bug go to: https://bugs.launchpad.net/canonical-devices-system-image/+bug/1370791/+subscriptions -- Mailing list: https://launchpad.net/~unity-api-bugs Post to : unity-api-bugs@lists.launchpad.net Unsubscribe : https://launchpad.net/~unity-api-bugs More help : https://help.launchpad.net/ListHelp