How to have operators highlighted in different color like Sublime Text?

[ghost]

Currently they are in the same color as variables, functions,...

[orbitalquark]

You would want to change your theme to set styles for `lexer.OPERATOR`. By default it is unset: https://github.com/orbitalquark/textadept/blob/96f58f1fa34fa50feead22df21b34412c1327da1/themes/light.lua#L62. You can copy one of Textadept's default themes to your *~/.textadept/themes/* directory, change that property, and then call `ui.set_theme()` from your *~/.textadept/init.lua* with that theme's name. If it's the default 'light' theme, then you don't have to do anything; Textadept uses it automatically.