October 28, 2016: installation of Xubuntu 16.04.1 LTS and then of Xubuntu 17.04 on LDLC computer Saturne SG4-I3-8-S9H7

Why switching from KDE to Xfce?

With KDE I get some instability after several suspend on RAM/wake up procedures (screenpaper that disappears, icons disappearing, etc.). And there is some slowness in the desktop environment, for instance:

I don’t want the search engine Baloo to run, since it is not enough scalable (see my previous installation accounts). And on use I have found that Thunderbird is far more scalable than Kontact: it seems that there is a scalability problem with Kontact databases when they are several Go large. Thunderbird has a fastest search, no hard drive working for *minutes* when a new mail is received.
after some uptime, on single click the Klipper popup (clipboard content) appears only after some delay, and after still some delay it appears in the desktop preview in the “Pager” app (the app to switch between desktops).
after some days of uptime, the device notifier in the panel bar is slow to display after a click. When it appears, a new item is displayed in the task manager (list of windows), but disappears after about 0.4s!
there are various graphical artifacts in the environment. For instance only some letters of text are displayed: here, see in particular the screenshot here. Unfortunately the bug is also present in Xfce. According to one of the comments at this page, the bug disappears with kernel 4.8. And indeed I have checked that it is no more here in Xubuntu 17.04 (kernel 4.10).
in some circumstances the screen locker never starts, letting the computer without protection.
I don’t like the black and white “flat” theme of the latest versions of KDE.
On another computer I have found that Xfce better supports a second screen put on a Display Port/USB converter. For some reason in KDE, disconnecting and connecting the screen wreaks havoc in the KDE display configuration and finally in the whole desktop. The display configuration in Xfce works better.

There weren’t such problems in KDE 3, and even in early KDE 4 versions. Another reason to switch to Xfce is to have a non-Qt desktop environment to test possible Qt applications I may develop (it is out of question of learning another framework). Xfce lacks some features compared to KDE, but it is not so much a problem.

My first idea was to stick to a LTS (long term support) version, namely 16.04, but as explained above I have switched to 17.04 to get a newer kernel. I have installed Xubuntu rather than Kubuntu and Xfce, so as to get all Xfce “candy” installed by default.

Installation

I have used the same installation procedure as in the past, without major problem: I ran the installation by clicking on the installer desktop icon in a live Xubuntu session (16.04.1 or 17.04) instead of a live Kubuntu session. It was still necessary to mount my encrypted partitions (in Thunar instead of Dolphin); then answer ’yes’ when the installer asks for trying to unmount these partitions. In my case, the bootloader has to be installed on /dev/sda, not the default choice /dev/dm-1.

Qt/KDE software I continue to use

Yet I will continue to use some Qt/KDE software:

kdesudo
konsole
okular
amarok
kruler
spectacle (replacement of ksnapshot; the latter one being no more available in Ubuntu 17.04).
kcolorchooser, in particular because it has a HSV color chooser (it allows to grey out the chosen color by playing on the V value).
kmag
gwenview
ktimer
kbibtex
kate
and muon instead of Synaptic.

Xfce panel applets I have installed

xfce4-goodies: contains “CPU Graph” and “Network Monitor” (where it is necessary to necessary to indicate the network device manually (enp4s0f2 in my case)), “DateTime”, “Clipman”.
Battery Monitor
PulseAudio Plugin (with pavucontrol as audio mixer)
I have put the “Display” menu in the panel by dragging it from the “Launcher” dialog and dropping it in the panel.

Xfce special tuning

to choose a desktop background directory, there is a bug (directories are greyed out). Workaround at here.
focus: in Settings -> Window Manager. It is useful to choose “Focus follows mouse” because with “click to focus”, when there is a text selection in a window, by clicking on the window to get focus the selection is lost.
roll up a window by a double click on its title bar: here: “Settings Manager” -> “Window Manager” -> “Advanced tab” -> “Double-click action” -> “Shade window”.
start applications at Xfce startup (e.g. Davmail): Settings -> Sessions and Startup -> Application Autostart.
Settings -> Sessions and Startup -> Advanced -> Lock screen before sleep.
Settings -> Keyboard -> Application Shortcuts: addition of the KDE program “ksnapshot” to the PrintScreen key, addition of “xkill” to CTRL+ALT+ESCAPE. Note that to escape the xkill cross the escape key does not work but a right click does.
Default applications associated to a file: right click on a file in Thunar -> Properties -> General -> Open With.
Map “suspend” to a key: as for ksnapshot above, with the command “xfce4-session-logout –suspend” instead.
Window manager -> style. In the button layout, drag and drop the circle “stick” from the hidden to the active layout.
appearance -> style: the default choice is ok. Other styles do not look better.

For a future installation, it may be interesting to read this in details.

Interesting in Xfce:

ALT + mouse wheel to zoom/unzoom on screen.
ALT + left click and move the mouse to move a window (I have been using it for years, this also works in KDE).
ALT + right click and move the mouse to resize a window (I have discovered that this also works in KDE).

Switching from Kontact to Thunderbird

As already said, I have switched to Thunderbird because of lack of scalability in akonadi and other stuff (mysql server working too hard due to my several tens of thousand mails, resulting in heavy hard disk usage). I have followed the indications here:

install the import/export tools for Thunderbird available here. Note that this module is not found by the search widget in Tools -> Add-ons.
create a new directory (e.g. INBOX_CUR) in “Local Folders” (not in a SMTP folder, otherwise all messages will be copied on a distant server).
import messages by right clicking on the local folder directory just created (e.g. “INBOX_CUR”), then ImportExportTools -> Import messages, go to the suitable directory (e.g. ~/.local/share/.local-mail/sent-mail/cur), select "All files", do CTRL+A to select all files, and click on "Open". Repeat the operation for every relevant directory: “new” and “cur” in inbox, sent-mail, etc.

Good in thunderbird: quick to search, quick to launch, no special hard disk use though several 10e4 messages. Filter very quick: Thunderbird menu (the one with three horizontal bars — not the main menu) -> View -> Messages -> Custom Views. Thunderbird is astonishingly fast to display tens of thousand of mails in its list widget. It is written in the GTK toolkit on Linux (see here; on Windows and Apple, native toolkits are used. It seems to be the same for firefox). It is interesting to note that “The French military uses Thunderbird and contributes to its security features, which are claimed to match the requirements for NATO’s closed messaging system.” (see here).

There are nice customizations to be done:

View -> Toolbars -> Customize -> Show -> Icons and Text (better than Icons beside Text)
View -> Toolbars -> Customize: drag and drop “Quick Filter” icon from Thunderbird, and “View” icon to Thunderbird (I have defined a custom view to see only the messages I have sent to my personal email from my work email — using the quick filter or the search does not allow to do that in an efficient manner). I don’t remove the “Chat” icon, though I will not use it for the time being.

There are however advantages of KMail/Kontact that are lost in Thunderbird, in particular:

the ability to have several identities associated to a single mail account. I have not copied all my Kontact identities in Thunderbird.
the same mail identities as in KMail are used in the newsgroup software KNode.
the number of messages in a Thunderbird directory is limited to some thousands.

I have moved all my mail up to now from ~/.local/share to ~/LOCAL_MAIL_KONTACT_DECEMBER_2016. I will probably remove it in the future if the switch to Thunderbird is satisfying. I have also removed akonadi stuff in ~/.local/share/akonadi/ and ~/.local/share/baloo/.

To activate the calendar in Thunderbird, it is sufficient to install the “xul-ext-lightning” package. In the preference dialog of the calendar, I have changed some settings, as activating default reminder one day before appointment, and make the week start on Monday (the latter was impossible in the last version of Kontact I used).

No problem to import the address book from Kontact in Thunderbird: run KAddressBook and File -> Export -> Export vCard 4.0 -> All contacts -> Export to One File. I have saved it in ~/Documents/personal_info/people_I_knew/. It is imported without problem in the Thunderbird address book: Tools -> Import -> Address Books -> Next -> vCard file. Then I have removed obsolete contacts from the Thunderbird address book, so as to avoid seeing them when I begin to type a name in the mail composer (it would be nice to be able to “deactivate” some directories of the address book). I can recover these addresses by looking at the people_I_knew directory.

To get color for the items in the calendar, I have used the extension “calendar-tweaks”: here, and chose “apply category color to event backgrounds” in the configuration dialog.

To get reminders for the contacts for which I have indicated birthdays in the address book, I have first tried Birthday Reminder (version 1.0.6.5), but after installation at Thunderbird restart a popup appears: “No birthday found in the address books” or something similar, though there are birthdays indicated for some of my contacts in my address book. So I did not insist and instead tried the extension ThunderBirthDay (version 0.8.2), following the installation guide:

Create a new calendar in Lightning by clicking File>New>Calendar... in the menu bar. Then choose "On My Computer" as location and "Birthdays from the Thunderbird addressbook" as type for your calendar. Also specify the address book to use as a source for birthdays. Finally choose a name for the new calendar.

After this indeed new events corresponding to birthdays appear in the calendar, and reminder popups are displayed at the right time. When a birthday is added in the address book, it appears some time later in the calendar, this time depending on the value set in the “properties” contextual menu of the calendar (right-click on the calendar created as explained above).

At some stage the calendar was deactivated, indicating to be incompatible with the too recent Thunderbird version. The solution has been so upgrade the package xul-ext-lightning Ubuntu package. After a Thunderbird restart it worked again.

To create a Usenet account: File -> New -> Other Accounts -> Newsgroup account. However, I can’t run KNode to copy my configuration, because KNode is not available in the Kubuntu 16.04 Kontact: see here. So I will set usenet later.

Firefox session lost

At some stage I have lost my previous session without being able to restore it (“History -> Restore Previous Session” greyed out).

$ cd ~/.mozilla/firefox/38z5cgik.default
$ rm -f sessionstore*js

After that Firefox enables the menu entry “History -> Restore Previous Session”, which probably loads sessionstore-backups/previous.js.

Nvidia drivers

I have installed some packages that in turn required the nvidia-367 package (the latest one in 16.04) to be installed. But after that, the CPU fan is always very high; for instance when running foobillard, one of my four threads corresponding to my dual-core CPU (Intel(R) Core(TM) i3-3110M CPU @ 2.40GHz) is 100% in use (see here: “Unlike hyper-threading, there are no tricks here — a dual-core CPU literally has two central processing units on the CPU chip”), and the CPU fan is almost at maximum. The solution has been to uninstall nvidia-367: the open source Nouveau driver is then used and after that everything is fine. The performance is the same as in 2012:

$ glxgears 
Running synchronized to the vertical refresh.  The framerate should be
approximately the same as the monitor refresh rate.
305 frames in 5.0 seconds = 60.923 FPS
302 frames in 5.0 seconds = 60.266 FPS
[...]

Note that I have not tried to get support for Optimus. As in 2012, the best option seems to be Bumblebee (cf here; see also here); installing the package "bumblebee" does not install nvidia drivers, and no CPU/fan problem appears.

libdvdcss (DVD encryption) support

$ wajig install libdvd-pkg
$ sudo dpkg-reconfigure libdvd-pkg

Other

I have installed xscreensaver; then a configuration icon appears in the Xfce Settings panel.
Remove “parole” media player (I use VLC instead).
To list hardware, I have installed hardinfo and lshw-gtk (see here). hwinfo is also available.
Add transparency when moving and resizing windows. No problem for this computer but on another one it resulted in complete compute freeze.
"Cycling through a list" for ALT+TAB
"Show windows from all workspaces or viewports", "Windows grouping: always".
Compose key: I choose "Right Win" in Settings -> Keyboard -> Layout. The combinations in ~/.XCompose are correctly managed.

Username mismatch

During installation I have called my user name "jscordi" instead of "jscordia": then a lot of things did not work anymore due to (i) broken absolute symlinks to /home/jscordia that no more exists (ii) /home/jscordia appearing in configuration files. The solution has been to create a symlink /home/jscordia pointing to /home/jscordi. I tried to move /home/jscordi in /home/jscordia, and changing rights in the whole /home/jscordia directory as:

$ chown -R . jscordia:jscordia

without success: when starting Xfce, the graphical environment is buggy.

KDE applications (Konsole, Skanlite, etc.)

Typing in xfce4-terminal:

$ konsole
** (konsole:18684): WARNING **: Couldn’t connect to accessibility bus: Failed to connect to socket /tmp/dbus-uuI6DSv5BV: Connection refused
Segmentation fault (core dumped)

Fortunately the problem is solved after a reboot.

Errors at package installation

When some packages are indicated are broken, the simplest solution is to use synaptic or muon that are able to list all broken packages. Then uninstall all of them.
After some manipulations, I obtained the error:
```
debconf: DbDriver "config": /var/cache/debconf/config.dat is locked by another process: Resource temporarily unavailable
```
Solution given here:
```
$ sudo fuser -v /var/cache/debconf/config.dat
```
fuser allows to see which process blocks some file; in other words it allows to access Linux kernel information. As a complementary tool, lsof lists the open files.

Perusal, Synthesis, Bliss