Improvements to terminal ui

[Alan Pope 🍺🐧🐱 🦄]

As discussed during the terminal meeting.

The terminal has limited space on a mobile device, and much of that is taken up with the header. In addition the terminal does not support multiple tabs. We'd like to improve the terminal and make it more consistent with other applications. With that in mind I propose the following changes:-

1. Remove top header
2. Add bottom edge swipe up (as per clock app) to reveal a list of tabs. By default we start with one "tab".
  * If only one tab is open we provide an option to open an additional tab as the first revealed option.
  * If more than one tab is open we reveal a list of open tabs (much like dialer lists previous callers) with the last option being to open a new tab
  * Pulling all the way up reveals a scrollable list of tabs
  * Once in the full reveal, we can swipe to delete tabs (much like clock can swipe to delete alarms)
3. Within the pull-up we re-implement the header which we removed from the main screen

This will also allow us to more easily support implementing bug 1202472

[Alan Pope 🍺🐧🐱 🦄 (popey)]

Here's a mock-up of what we discussed.

[Filippo Scognamiglio (flscogna)]

Very nice mockup Alan!

[Alan Pope 🍺🐧🐱 🦄 (popey)]

As discussed on the last meeting, lets focus on just adding the tab support and bottom edge, and leave the header where it is for now.

[Kill Animals (kill-animals)]

Very nice mockup. Is that plus sign though going to obfuscate what the user is inputting?

[Evan McIntire (mcintire-evan)]

Is this still a valid bug? From the date, I can see it is from before the rewrite began, and much of what is discussed here has been implemented in the current version. Maybe we could update this to say what still needs to be done to improve the UI as it stands?

[Cesar Herrera (chg1)]

If the keyboard were transparent we could see text in all parts of the screen

[Stefano Verzegnassi (verzegnassi-stefano)]

@Cesar: I guess we can't do that, since the keyboard is not part of the application but it's a separate window which overlaps the app itself. Also, the Mailit keyboard does not seem to provide any extension that would allow to access to its style properties.

@Alan, @Evan: This is a nice concept, and would allow us to resolve lp:1400329 [1] too.
Since we also have to fix lp:1539635 [2], we need a (better?) solution for the floating buttons, and Alan's proposal could help us a lot. However, I'm not sure how this would behave with the OSK (would bottom edge gesture be still available when the OSK is visible? should we force user to close the OSK in order to switch tab or access to the settings?)

Does it make sense to add ubuntu-ux for an input?

[1] "[Reboot] Hide the settings button" - https://bugs.launchpad.net/ubuntu-terminal-app/+bug/1400329
[2] "Make tabs visible in desktop mode" - https://bugs.launchpad.net/ubuntu-terminal-app/+bug/1539635

[Evan McIntire (mcintire-evan)]

Sorry Stefano, just now saw this

I think it would be worth having ubuntu-ux look over the idea; personally I feel that closing the OSK and then swiping up is a bit clunky, but I still like the idea (I'd have to try it out to really know how it is though)