GNOME’s default text editor, Gedit, includes a powerful plugin system similar to Firefox’s. There are useful plugins available for both programmers and regular users.
Enable, disable, and configure plugins from the Plugins tab in Gedit’s preferences dialog. There’s no need to restart Gedit, plugins are enabled immediately.
A small selection of plugins are installed by default with Gedit, and some are also even enabled. Here’s a few from the default selection to try: