Created attachment 74746 [details]
Screenshot showing the wrong behavior of the icons.
The icons for the Undo/Redo buttons are the same for both LTR and RTL interfaces. The undo icon should point to the left in LTR and to right in RTL and vice versa for the redo.
Wrong behavior: |--> redo|<-- undo|
Right behavior: |<-- redo|--> undo|
I've solved this and it has already been merged with master https://gerrit.libreoffice.org/#/c/1712/
Please note that currently special icons are assigned per language rather than interface (possibly for people to create their own Bold/Italic/Underlined buttons), hence I have assigned the RTL icons to each of Arabic (ar), Hebrew (he) and Farsi (fa).
Committed to master as c56651e76c2dc8068d53406dcdd6cb6bd1bd9bce
and to 4-0 branch as 7e852d137ea8cd4898e67747d411e0de8710aedc
Verified on 4.0.0 and master.