Options dialog box can be accessed by selecting Settings | Options... menu command.
Fonts: This section lists all fonts available for every Indian script. You can select default font and size for every script.
Indian numerals: Use Indian numerals instead of English numerals
Auto completion: Enable/Disable auto completion. Read auto completion topic
Tamil consonant numerals: Subscript numerals (ex: க₂, க₃, க₄) are used for க, ச, ஜ, ட, த, ப consonants if this option is selected
Screen color: Specifies the screen color