<fontconfig>
<match>
<test name="lang" compare="contains">
<string>ar</string>
</test>
<test name="family">
<string>sans-serif</string>
<edit name="family" mode="prepend" >
<string>KacstNaskh</string>
</edit>
</match>
<alias>
<family>KacstNaskh</family>
<default>
<family>sans-serif</family>
</default>
</alias>
</fontconfig>