per Nick Koretsky:

| none of this conflicts with trinity on debian. Either ubuntu pacakges are

| broken or you installed some libs from ppas and now have version conflicts.

| Start aptitude in interactive mode and look for what exactly brakes when

| you add this packages.

here's what happens when i try to install protonmail-bridge:

Selecting previously unselected package protonmail-bridge.

(Reading database ... 1534488 files and directories currently installed.)

Preparing to unpack .../protonmail-bridge_1.0.3-1_amd64.deb ...

Unpacking protonmail-bridge (1.0.3-1) ...

dpkg: dependency problems prevent configuration of protonmail-bridge:

protonmail-bridge depends on qt5-default; however:

  Package qt5-default is not installed.

protonmail-bridge depends on libqt5designer5; however:

  Package libqt5designer5 is not installed.

protonmail-bridge depends on libqt5multimediawidgets5; however:

  Package libqt5multimediawidgets5 is not installed.

protonmail-bridge depends on libqt5quickwidgets5; however:

  Package libqt5quickwidgets5 is not installed.

dpkg: error processing package protonmail-bridge (--install):

dependency problems - leaving unconfigured

Processing triggers for gnome-menus (3.10.1-0ubuntu2) ...

Processing triggers for desktop-file-utils (0.22-1ubuntu1.1) ...

Processing triggers for mime-support (3.54ubuntu1.1) ...

Errors were encountered while processing:

protonmail-bridge

RESULT=1

so let's install the dependencies, beginning with qt5-default:

Reading package lists... Done

Building dependency tree

Reading state information... Done

You might want to run 'apt-get -f install' to correct these:

The following packages have unmet dependencies:

protonmail-bridge : Depends: libqt5designer5 but it is not going to be installed

                     Depends: libqt5multimediawidgets5 but it is not going to be installed

                     Depends: libqt5quickwidgets5 but it is not installable

qt5-default : Depends: qtbase5-dev but it is not going to be installed

N: Ignoring file 'brave-trusty.listgrep' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension

N: Ignoring file 'brave*' in directory '/etc/apt/sources.list.d/' as it has no filename extension

N: Ignoring file 'brave-trusty.listgrep' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension

N: Ignoring file 'brave*' in directory '/etc/apt/sources.list.d/' as it has no filename extension

N: Ignoring file 'brave-trusty.listgrep' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension

N: Ignoring file 'brave*' in directory '/etc/apt/sources.list.d/' as it has no filename extension

E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).

so let's do what it suggests and run apt-get -f install:

Reading package lists... Done

Building dependency tree

Reading state information... Done

Correcting dependencies... Done

The following packages were automatically installed and are no longer required:

  acpi amarok-common-trinity amarok-engine-xine-trinity amarok-trinity

  arts-trinity bluetooth bluez-utils crystalcursors

  desktop-effects-tde-trinity dmz-cursor-theme fonts-arabeyes foo2zjs

  fortune-mod fortunes-min fotoxx-common gir1.2-ges-1.0

  gir1.2-gst-plugins-base-0.10 gir1.2-gst-plugins-base-1.0

  gir1.2-gstreamer-0.10 gir1.2-gstreamer-1.0 gstreamer1.0-gnonlin

  gtk-qt-engine-trinity gtk3-tqt-engine-trinity gwenview-trinity

  kaffeine-trinity karm-trinity katapult-trinity kbstate-trinity

  kdbusnotification-trinity keep-trinity kmag-trinity kmailcvt-trinity

  kmousetool-trinity kmplayer-base-trinity kmplayer-konq-plugins-trinity

  konversation-trinity kopete-trinity kpf-trinity kppp-trinity krdc-trinity

  krfb-trinity ksplash-engine-moodin-trinity ksystemlog-trinity

  ktorrent-trinity kubuntu-default-settings-trinity

  kubuntu-konqueror-shortcuts-trinity kvkbd-trinity landscape-client

  landscape-common lftp libavahi-tqt-1 libccfits0 libcfitsio3

  libdbus-tqt-1-1c2 libges-1.0-0 libifp4 libjs-sphinxdoc libllvm3.8v4

  libmp4v2-2 libnjb5 libqt5concurrent5 libraw9 librsync1 libscim8c2a

  libwayland-dev min12xxw pnm2ppa powermanagement-interface pxljr

  python-gst-1.0 python-pylibacl python-pyxattr qt4-tqt-theme-engine qt5-qmake

  qtbase5-dev-tools rdesktop rdiff-backup scim-bridge-client-qt scim-im-agent

  scim-modules-socket screen speedcrunch splix strigi-daemon synaptic-trinity

  tqca-tls ttf-arabeyes ttf-arphic-ukai ttf-arphic-uming ttf-lao

  ttf-malayalam-fonts ttf-thai-tlwg ttf-unfonts-core

Use 'apt-get autoremove' to remove them.

The following packages will be REMOVED:

  fotoxx gimp-gmic gir1.2-clutter-gst-1.0 gir1.2-clutter-gst-2.0

  gir1.2-gtkclutter-1.0 kubuntu-desktop-trinity libchamplain-0.12-0

  libchamplain-gtk-0.12-0 libclutter-gst-1.0-0 libxatracker2 luminance-hdr

  pitivi protonmail-bridge xorg xserver-xorg-video-vmware

0 upgraded, 0 newly installed, 15 to remove and 0 not upgraded.

1 not fully installed or removed.

After this operation, 33.1 MB disk space will be freed.

see the problem? among other things, i believe that xorg is crucial to full enjoyment of the tde experience.