This function is used to turn character mirroring on or off.
Character mirroring is the act of replacing a mirrorable glyph
(character), eg. Left paranthesis, with the matching glyph,
eg. Right paranthesis, in a right-to-left resolved context.
If your rendering engine does mirroring itself, you may want to
turn it off here.
This flag is on by default.
This function is deprecated and only used with other deprecated functions.