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Kubuntu 18.04 Troubleshooting

Solving my problems with a Lenovo Thinkpad T450s:

I ended up putting the following scripts in /lib/systemd/system-sleep.

This script fixes that touchpad scrolling with a two finger gesture does not work anymore after resume:
case "$1" in
        modprobe -r psmouse
        modprobe psmouse
        echo "modprobe script finished @ `date`" >> /tmp/modprobescript

And this script is an ugly workaround for notifications and global shortcuts not working anymore after resume (see also
sleep 6
export DISPLAY=:0
sudo -u markus kcmshell5 khotkeys &
sleep 1
killall kcmshell5

Inkscape Tooltips

To avoid nearly unreadable (white on white) tooltips in Inkscape disable Apply colors to non-Qt applications in the KDE System Settings under Colors.

Eclipse & SVN

Using Eclipse 2018.09 and Kubuntu 18.04:

Subclipse by default uses JavaHL - this does not work well, for each svn update it takes Gigabytes of RAM and a long time. What works: switch to the pure Java implementation (SVNKit) in Preferences > SVN!

Subversive is no longer maintained, don't use it!

File Associations / Default Applications

Note: this research was done on Kubuntu 15.10 using KDE 5

Nowadays MIME types and .desktop files are involved in deciding which programs are used to open a certain file. See these wiki entries for Arch Linux (recommended in-depth explanation) and Debian.

KDE uses ktraderclient5 to determine the default program. Also xdg-open uses this program (see the function defapp_kde() in xdg-mime or the output of xdg-mime query default application/pdf). It returns useful defaults such as using Okular to open pdfs even if Gimp is installed (ktraderclient5 –mimetype application/pdf). However, programs not relying on ktraderclient5 (such as Firefox) won't get these defaults as they are not stated in any mimeapps.list file. (FIXME: where do the defaults actually come from? Maybe dig into the code...)

As soon as you explicitly configure program preferences with Dolphin the defined program order is written to ~/.local/share/applications/mimeapps.list. The order of entries displayed in Dolphin is reflected in the section [Added Associations]. The section [Default Applications] is filled in as well, but it seems that KDE ignores the default set there and sticks to the first program in [Added Associations].

The most useful way I identified to get consistent for all applications (KDE and non-KDE) is to explicitly set defaults in ~/.local/share/applications/mimeapps.list, which will be updated for all programs when using the GUI method in Dolphin.

[Default Applications]

Missing Ark Context Menus

sudo ln -s /usr/share/kde4/servicetypes/konqpopupmenuplugin.desktop /usr/share/kservicetypes5/

KDE 4 & Eclipse problems

Freezes when Debugging GUIs

Using KDE 4.11 (Kubuntu 14.04) the whole workspace freezes when debugging GUIs, e.g. Java FX. Only switching to the console and killing the started program makes the desktop responsive again.

Solution: pass the VM argument -Dsun.awt.disablegrab=true.


Alternative solution: System Settings > Application Appearence > GTK > use “Raleigh” as GTK2 theme

The xfce gtk2 engine should also work (and is less ugly): apt install gtk2-engines-xfce

kubuntu.txt · Last modified: 2019/04/11 08:16 by mstraub