Gedit transparent background

Some gnome applications (usual ones: gedit, gnome-calculator) can suddenly get looking incorrect (transparent background, visual artifacts, etc).

The reason could be a change in:
- Settings => Region & Language => Manage Installed Languages => Keyboard input method system
- Language Support => Keyboard input method system

Solution:

- remove ~/.xinputrc
- reboot

`Error! Could not locate dkms.conf file`

- adapt /usr/sbin/dkms script 

to be more informative when error logging. You can change the line 527 (or similar on your system):

[[ -r $read_conf_file ]] || die 4 $"Could not locate dkms.conf file." \

to something like

[[ -r $read_conf_file ]] || die 4 $"Could not locate $read_conf_file file." \

to see where exactly is the problem located.

- dkms status

There should be valid output, without error messages.
If any dkms.conf file is not found:
- investigate sources and configs existing in the system (see commands below)
- remove "bad" modules (e.g. sudo rm -rf /var/lib/dkms/nvidia/)
- rebuild existing dkms modules

- ls -l /var/lib/dkms

to know what dkms modules are in the system

- ls /usr/src/*/dkms.conf

check existing dkms config files

- sudo dpkg-reconfigure virtualbox-dkms

rebuild dkms modules (here is `virtualbox-dkms` as an example)