State of Okular in Ubuntu 17.10?

With Ubuntu 17.10, Okular (installed through the Ubuntu repositories, i. e. apt install okular) seems to work a lot worse than in previous versions. This is both on Wayland and on the X session. Here is a screenshot:

For example: As you can see, only the item “Contents” in the left sidebar has an icon. The other ones (“Thumbnails”, “Reviews”, “Bookmarks”) should have icons as well (see e. g. this screenshot).

Moreover, when I open Okular from the Terminal, I get a bunch of output:

inotify_add_watch("/home/user/.config/ibus/bus/9f77c45ee0ec4b6a89aaaa7669ff56c1-unix-0") failed: "No space left on device"
Invalid Context= "stock" line for icon theme:  "/usr/share/icons/ubuntu-mono-dark/stock/16/"
Invalid Context= "stock" line for icon theme:  "/usr/share/icons/ubuntu-mono-dark/stock/22/"
Invalid Context= "stock" line for icon theme:  "/usr/share/icons/ubuntu-mono-dark/stock/24/"
Invalid Context= "stock" line for icon theme:  "/usr/share/icons/ubuntu-mono-dark/stock/32/"
Invalid Context= "stock" line for icon theme:  "/usr/share/icons/ubuntu-mono-dark/stock/48/"
Invalid Context= "stock" line for icon theme:  "/usr/share/icons/ubuntu-mono-dark/stock/64/"
Invalid Context= "stock" line for icon theme:  "/usr/share/icons/ubuntu-mono-dark/stock/128/"
Invalid Context= "stock" line for icon theme:  "/usr/share/icons/ubuntu-mono-dark/stock/16/"
Invalid Context= "stock" line for icon theme:  "/usr/share/icons/ubuntu-mono-dark/stock/22/"
Invalid Context= "stock" line for icon theme:  "/usr/share/icons/ubuntu-mono-dark/stock/24/"
Invalid Context= "stock" line for icon theme:  "/usr/share/icons/ubuntu-mono-dark/stock/32/"
Invalid Context= "stock" line for icon theme:  "/usr/share/icons/ubuntu-mono-dark/stock/48/"
Invalid Context= "stock" line for icon theme:  "/usr/share/icons/ubuntu-mono-dark/stock/64/"
Invalid Context= "stock" line for icon theme:  "/usr/share/icons/ubuntu-mono-dark/stock/128/"

The messages about the icon theme might be related to the missing icons. The first line apparently means that the limit of inotify watches has been reached – why is that happening?

Lastly, the UI theme looks nothing like other applications in Ubuntu (I guess this is a problem with Qt applications in general?) – look at the scroll bars, for example. I suppose this has to do with the move back to GNOME? It used to be much better in Ubuntu versions before 17.10.

Is there any way to fix/work around these issues?

As another data point, there is the question “Okular instances do not group under single icon in desktop dock on Ubuntu 17.10”, but that already has a solution in the link.

Install qt5ct:

sudo apt install qt5ct

Run:

qt5ct --platformtheme qt5ct

and set the icon-theme to breeze. (You may do other modifications as you wish)

Set the appropriate evironment variable:

sudo nano /etc/environment

and add this line:

QT_QPA_PLATFORMTHEME="qt5ct"

Reboot.

If this doesn't work continue with the following: Then copy the okular .desktop file to your home folder:

cp /usr/share/applications/org.kde.okular.desktop ~/.local/share/applications

Modify the copied .desktop file by changing the line:

Exec=okular %U

to

Exec=okular --platformtheme qt5ct %U

Open the ~/.local/share/applications folder in Files and run Okular. It will ask you to trust the application the first time.

Done.

My current status:

1. Missing icons: I found a solution to this in a comment on Launchpad bug #1698656 (“navigation panel icons missing on standard install of 17.04”):

   As a workaround, what worked for me was:

   $ sudo apt install systemsettings kde-config-gtk-style kde-config-gtk-style-preview oxygen-icon-theme

   • systemsettings for the app systemsettings5;

   • kde-config-gtk-style enables the Appearance module in systemsettings5;

   • kde-config-gtk-style-preview allows previewing the themes without restarting the GTK applications;

   • oxygen-icon-theme is an alternative theme to use in KDE applications.

   Then, run systemsettings5, click on Application Style, select Oxygen as a Fallback theme, click on Apply.

   I used “Breeze” instead of “Oxygen” as a fallback theme, though (because I like it more).

2. Error messages on the terminal: Still unsolved, although the issue of running out of inotify watches seems to have disappeared?

3. Inconsistent UI theme (e. g. scroll bars): Still unsolved.