On screen keyboard transparent - buffer not updated

The on screen keyboard is unusable on frieza_arm64/staging. It's just not displayed.

$ system-image-cli -i
current build number: 116
device name: frieza_arm64
channel: ubuntu-touch/staging/ubuntu
last update: 2017-01-06 12:22:32
version version: 116
version ubuntu: 20170106
version device: 20161014.0
version custom: 20170106

Note you'll need to downgrade dbus and reboot (bug #1654365):

$ sudo apt install {dbus{,-x11},libdbus-1-3}=1.10.6-1ubuntu3.1
$ sudo reboot

[2017-01-06:14:06:06.521] qtmir.surfaces: MirSurface[0x1c4a0820,"-"]::MirSurface(type=input Method,state=restored)
[2017-01-06:14:06:06.522] qtmir.surfaces: Session[0x1c571960,name="maliit-server"]::registerSurface(surface=qtmir::MirSurface(0x1c4a0820))
[...]
[2017-01-06:14:06:06.630] qtmir.surfaces: MirSurface[0x1c4a0820,"-"]::setInputBounds(QRect(0,1159 1200x761))
[2017-01-06:14:06:06.862] qtmir.surfaces: MirSurface[0x1c4e2f00,"unity8-dash"]::setFocused(false)
[2017-01-06:14:06:06.862] qtmir.applications: Application["unity8-dash"]::focusedChanged(false)
[2017-01-06:14:06:06.862] qtmir.surfaces: MirSurface[0x1c4a0820,"-"]::setFocused(true)
[2017-01-06:14:06:06.862] qtmir.surfaces: MirSurface[0x1c4a0820,"-"]::setReady()
[2017-01-06:14:06:06.863] qtmir.surfaces: Session[0x1c571960,name="maliit-server"]::prependSurface(surface=qtmir::MirSurface(0x1c4a0820))
[2017-01-06:14:06:06.863] qtmir.surfaces: Session[0x1c571960,name="maliit-server"]::setState(state=running)
[2017-01-06:14:06:06.863] toplevelwindowmodel: setFocusedWindow(Window[0x1c3958a0, id=3, MirSurface[0x1c4a0820,"MaliitOnScreenKeyboard"]])
[2017-01-06:14:06:06.864] qtmir.surfaces: MirSurface[0x1c4a0820,"-"]::setKeymap("us")
[2017-01-06:14:06:07.120] qtmir.surfaces: MirSurface[0x1c4a0820,"-"]::dropPendingBuffer() dropped=0 left=1 - failed to upate texture

That last one suggests unity8 didn't properly pick the input method up.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: unity8 8.15+16.04.20161215-0ubuntu1 [origin: LP-PPA-ci-train-ppa-service-stable-phone-overlay]
Uname: Linux 3.10.93+ aarch64
ApportVersion: 2.20.1-0ubuntu2.4
Architecture: arm64
Date: Fri Jan 6 14:05:11 2017
SourcePackage: unity8
UpgradeStatus: No upgrade log present (probably fresh install)