Preview window/process left open after exit

[Strahinja]

I'm using the latest repo version of cfiles, c225a0d, and it seems it also has an issue with ueberzug, which was fixed some time ago in ueberzug itself. (Reference: ueberzug 1, ueberzug 2, fontpreview-ueberzug.) To reiterate what I stated in the issue (and which currently applies to cfiles as well),

preview window stays open even after exiting the fontpreview-ueberzug program by pressing Esc. Also a process with the command line /usr/bin/python /usr/bin/ueberzug layer --parser simple --silent is left open. When killed (for example, by pskill -9 ueberzug, the parameter -9 is necessary), the leftover preview window disappears. This was a known issue in ueberzug, which was subsequently fixed

In addition, in cfiles multiple image preview windows stay open while browsing through a folder containing multiple images.