When I was travelling recently I found that if I plugged into a USB battery overnight to charge my phone, when I got up the next morning the phone didn't have any more power than when I started.
Turns out the reason is: when the phone decides the battery is full, it stops drawing current. The battery then decides that charging is over and automatically switches off. The phone then decides that it's been unplugged and turns the screen on. I had set the phone to not automatically switch the screen off, so it just left the screen on all night. The next morning it was as if it had never charged.
So I have the following suggestions:
1) Just don't turn the screen on when the user unplugs the charger
2) If the intention is to let the user know that the charger has been unplugged, pop up a message. Just turning the screen on isn't very useful feedback.
3) If you are turning the screen on automatically it "doesn't count" wrt the user's "automatically turn off screen after..." setting. This should always be just a few seconds.
4) If the user has configured the phone to not automatically switch off the screen, don't automatically turn it on either
5) Give me a few more options for automatically switching off the screen - 1, 2, 3, 4, 5 and 10 is a lot of resolution at the low end. Where is 30mins and 1hour?
P.S. this has nothing to do with webbrowser-app but I still can't figure out how to search launchpad for Ubuntu touch packages.
===============UX comment===================
I will try to address all the points raised in the bug description.
1) is invalid, we should turn on the screen when the user unplugs
the charger and possibly show a message reminding the user to unplug
the charger from the wall socket (if any).
I agree with 2), the system should show a system message as well. This is already specified as one of the usecases of the new notifications system UX (which hasn't been implemented yet).
https://docs.google.com/document/d/1xDSZ_dnAMAlhgFnnyjJEibaITXjVLp1_pnj_tATNm9I (private link)
I agree with 3) and this behaviour is already specified in the Screen blanking policy, that means it is on the plan to implement it (if it's not already)
https://docs.google.com/document/d/1RBoVknCLZ4GQ8E_iVftd3i_KmdxI5d6JrBt7i5EDZO0 (private link)
4) is taken care of by implementing 3)
Point 5) is valid but requires a new bug which should also specify the usecases when those longer values would be needed, so that UX designers can better understand the needs and the reasons behind a UX suggestion :)
Matthew, could you please file that bug? :)
Point 6) (the one presented in comment #1) is valid but requires a new bug, mentioning the usecases, just like 5). I have to say I am not really into that feature, because the screen backlight of devices like the Meizu MX4 probably consumes more power than a USB port provides (which is usually 500mA). So it needs special care and convincing usecases :)
Matthew, could you please file that bug, specifying some usecases when this feature would be really handy? :) I can't promise we will implement it, but we can discuss it ;)
Oh, another option:
* Provide a "do not automatically switch off screen when connected to charger" option. That would also avoid the need for me to configure it to never switch off.