[Dialer] dialer screen focussed after receiving a call

It is also very bad because of no lock screen is active after the call. On the BQ phone it presses some phone number digits while the phone is in the trouser pocket.

Status changed to 'Confirmed' because the bug affects multiple users.

The incoming call screen is currently a screen in the Phone app. Accepting the call switches to the app. How, then, could the desired behavior be implemented? Unity would have to remember where in the stack the Phone app was previously (if it was even running at all). The Phone app would have to tell Unity that the call was over. Then Unity would have to move it back to its previous position in the app stack. That's a lot of special-casing, and it's hard to see how any other VoIP app could do the same. (And on a PC where the app wasn't full-screen, that shuffling would look weird.)

If the call window was a parentless dialog instead, whether full-screen or not, it could float on top of whatever app you happened to be using at the time (even if that happened to be the Phone app). Once the call finished, the dialog would go away, and you'd be back where you were without any app shuffling.

Per mpt I don't think we have a decided design direction on this

We would need input from design, but ofono sends a signal over dbus when a call ends http://pastebin.ubuntu.com/14600960/
We could have unity8 listen for this and restore focus to the n-1 app in the application manager stack. Obviously there are a lot of edge cases here, but this wouldn't be _too_ hard in theory and any 3rd party dialer app (that uses ofono) would behave the same. An API would probably be required for voip apps though.

Specification updated. <https://goo.gl/ibyRO3> (Canonical-only link, sorry) “When the device detects an incoming call: 1. A parentless dialog should appear instantly, showing the contact display name and (if there is one) the contact photo for the caller. It is parentless so that if you decline, or when the call ends, you will be returned to the window you were using rather than the Phone app.”

@Matthew this spec already describes the current behavior. The issue is that when a call is accepted, the dialer app is launched, and the call is ended using the app rather than the parentless dialog. It would take considerable effort to get the dialer app to run inside a dialog, and the dialer app would need to be modified in such a way that pressing end would dismiss the dialog (a dialog that wasn't created by the app itself). This would also not solve the problem for 3rd party dialers. I can prototype my other solution if you'd like. I'm also at a sprint right now, so I can get some technical input from other folks and see what other solutions are possible.