Eu o consertei fazendo o seguinte na seguinte ordem:
sudo ppa-purge ppa:kubuntu-ppa/backports
sudo apt-get install -f
sudo apt autoremove
sudo apt-get install unity-tweak-tool
Quando fiz o ppa-expurgo, esse foi o resultado:
The following package was automatically installed and is no longer required:
libxcb-xinerama0
Use 'sudo apt autoremove' to remove it.
The following additional packages will be installed:
packagekit-backend-aptcc python3-packagekit
Suggested packages:
libqt4-declarative-folderlistmodel libqt4-declarative-gestures
libqt4-declarative-particles libqt4-declarative-shaders qt4-qmlviewer
libqt4-dev libqt5libqgtk2 qt4-qtconfig packagekit-backend-smart
Recommended packages:
packagekit
The following packages will be REMOVED:
libpackagekit-glib2-18
The following NEW packages will be installed:
packagekit-backend-aptcc python3-packagekit
The following packages will be DOWNGRADED:
aptdaemon aptdaemon-data breeze-icon-theme gir1.2-packagekitglib-1.0
libqt4-dbus libqt4-declarative libqt4-network libqt4-script libqt4-sql
libqt4-sql-sqlite libqt4-xml libqt4-xmlpatterns libqt5core5a libqt5dbus5
libqt5gui5 libqt5network5 libqt5opengl5 libqt5printsupport5 libqt5qml5
libqt5quick5 libqt5sql5 libqt5sql5-mysql libqt5sql5-sqlite libqt5svg5
libqt5waylandclient5 libqt5webkit5 libqt5widgets5 libqt5x11extras5
libqt5xml5 libqtcore4 libqtdbus4 libqtgui4 packagekit packagekit-tools
python-aptdaemon python-aptdaemon.gtk3widgets python3-aptdaemon
python3-aptdaemon.gtk3widgets qdbus qtchooser qtcore4-l10n
qttranslations5-l10n qtwayland5
0 upgraded, 2 newly installed, 43 downgraded, 1 to remove and 0 not upgraded.
Need to get 34.1 MB of archives.
After this operation, 28.5 MB of additional disk space will be used.
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E a instalação da ferramenta de ajuste de unidade resultou nisso:
sudo apt-get install unity-tweak-tool
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following additional packages will be installed:
libandroid-properties1 libhardware2 libhud2 libhybris libhybris-common1 libmedia1 liboxideqt-qmlplugin liboxideqtcore0 liboxideqtquick0 libqt5feedback5 libqt5multimedia5 libqt5organizer5
libqt5positioning5 libqt5quicktest5 libqt5test5 libubuntugestures5 libubuntutoolkit5 libunity-action-qt1 libunity-webapps0 qml-module-qt-labs-folderlistmodel qml-module-qt-labs-settings
qml-module-qtfeedback qml-module-qtgraphicaleffects qml-module-qtquick-layouts qml-module-qtquick-window2 qml-module-qtquick2 qml-module-qttest qml-module-ubuntu-components
qml-module-ubuntu-layouts qml-module-ubuntu-onlineaccounts qml-module-ubuntu-performancemetrics qml-module-ubuntu-test qml-module-ubuntu-web qtdeclarative5-accounts-plugin
qtdeclarative5-qtquick2-plugin qtdeclarative5-ubuntu-ui-toolkit-plugin qtdeclarative5-unity-action-plugin suru-icon-theme ubuntu-mobile-icons ubuntu-ui-toolkit-theme unity-webapps-common
unity-webapps-qml unity-webapps-service webapp-container webbrowser-app
Suggested packages:
xul-ext-unity | unity-chromium-extension qtdeclarative5-online-accounts-client0.1 qtdeclarative5-ubuntu-content1 qtdeclarative5-ubuntu-download-manager0.1
qml-module-ubuntu-onlineaccounts-client
The following NEW packages will be installed:
libandroid-properties1 libhardware2 libhud2 libhybris libhybris-common1 libmedia1 liboxideqt-qmlplugin liboxideqtcore0 liboxideqtquick0 libqt5feedback5 libqt5multimedia5 libqt5organizer5
libqt5positioning5 libqt5quicktest5 libqt5test5 libubuntugestures5 libubuntutoolkit5 libunity-action-qt1 libunity-webapps0 qml-module-qt-labs-folderlistmodel qml-module-qt-labs-settings
qml-module-qtfeedback qml-module-qtgraphicaleffects qml-module-qtquick-layouts qml-module-qtquick-window2 qml-module-qtquick2 qml-module-qttest qml-module-ubuntu-components
qml-module-ubuntu-layouts qml-module-ubuntu-onlineaccounts qml-module-ubuntu-performancemetrics qml-module-ubuntu-test qml-module-ubuntu-web qtdeclarative5-accounts-plugin
qtdeclarative5-qtquick2-plugin qtdeclarative5-ubuntu-ui-toolkit-plugin qtdeclarative5-unity-action-plugin suru-icon-theme ubuntu-mobile-icons ubuntu-ui-toolkit-theme unity-tweak-tool
unity-webapps-common unity-webapps-qml unity-webapps-service webapp-container webbrowser-app
0 upgraded, 46 newly installed, 0 to remove and 0 not upgraded.
Need to get 45.1 MB of archives.
After this operation, 166 MB of additional disk space will be used.
Do you want to continue? [Y/n]
Eu tive essa ideia depois de analisar a resposta aqui
Eu acho que o motivo foi que quando fiz a atualização atualizei algumas das dependências exigidas por outros pacotes usando o Kpuntu ppa. Mas as versões desatualizadas eram necessárias para os pacotes funcionarem corretamente. Eu não sei qual pacote foi exatamente.