It is fairly pointless to have a comment like "--- RTL --- (mirror
mouse pos)" in front of code that obviously is related to RTL anyway,
like "if( AllSettings::GetLayoutRTL() )". Also, the fact that many
comment were exactly the same indicates that they has been added as an
in-line version control change marker.

In other places, comments were informational, but no need for them to
include yet another metasyntax, "--- RTL ---". Just "RTL:" works fine.

Change-Id: I20feef308ed8ac9d32a8bf440fc20b442753c4ff