Arabic is sometimes written with diacritical vowel marks, which are placed either above or below each letter of the word. Many multipurpose fonts, which are not designed specifically for Arabic, place some of these marks in the empty space between lines, outside of the space reserved for line height. Writing Arabic in LibreOffice Writer, these marks don't become visible while typing but only after the page view has changed once.
See the attached series of screenshots, where the first screenshot has been taken while typing. The first letter of the first word (reading from right to left) should have two diacritical marks: ء and a diagonal line above the letter: أَ. Only the lower half of the ء mark is visible and the diagonal line not at all. The second letter of the same word has a circle on top of it but only the lower half of it is visible. Equally so for the third word of the sentence بِبَرْنَامِجِ, where the last letter of the word has a diagonal line below, but it is not visible at all. The second screenshot has been taken after I scrolled the page down by a couple of screens and then scrolled back. Now all the diacritics are shown as they should. In the third screenshot I have deleted all of the text I typed but as you can see, some parts of the diacritics are still visible above the line. If I scroll down and back, they would disappear. If you want to test it yourself, the sentence I wrote reads "أَكْتُبُ هُنَا بِبَرْنَامِجِ لِيبَرْ أُفِيسْ".
As a user, I would expect the diacritics to be visible as soon as I type them, and for them to be removed from the screen immediately when I delete the word.
Description: Ubuntu 17.10
Release: 17.10
libreoffice-writer:
Installed: 1:5.4.6-0ubuntu0.17.10.1
Candidate: 1:5.4.6-0ubuntu0.17.10.1
Version table:
*** 1:5.4.6-0ubuntu0.17.10.1 500
500 http://mr.archive.ubuntu.com/ubuntu artful-updates/main amd64 Packages
100 /var/lib/dpkg/status
1:5.4.5-0ubuntu0.17.10.5 500
500 http://security.ubuntu.com/ubuntu artful-security/main amd64 Packages
1:5.4.1-0ubuntu1 500
500 http://mr.archive.ubuntu.com/ubuntu artful/main amd64 Packages
ProblemType: Bug
DistroRelease: Ubuntu 17.10
Package: libreoffice-writer 1:5.4.6-0ubuntu0.17.10.1
ProcVersionSignature: Ubuntu 4.13.0-41.46-generic 4.13.16
Uname: Linux 4.13.0-41-generic x86_64
ApportVersion: 2.20.7-0ubuntu3.8
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Mon May 21 16:17:03 2018
InstallationDate: Installed on 2017-02-13 (462 days ago)
InstallationMedia: Ubuntu 16.10 "Yakkety Yak" - Release amd64 (20161012.2)
ProcEnviron:
TERM=xterm-256color
PATH=(custom, no user)
XDG_RUNTIME_DIR=<set>
LANG=fi_FI.utf-8
SHELL=/bin/bash
SourcePackage: libreoffice
UpgradeStatus: Upgraded to artful on 2017-11-05 (196 days ago)
Second screenshot showing all the diacritics in full.