Hi, I'm new to plugin development and am looking to work on something for IntelliJ community edition. The impact of the plugin would involve UI elements such as highlighting or icons to the side of the text editor, but I can't find much in the way of good tutorials or examples for this. The 'main types of plugins' page I found linked to the Background Image plugin which is very old and I can't even get to work, hardly useful to learn from.
So far I've managed to boot up a plugin that adds a do-nothing option to one of the existing menus, but I haven't found a good source on how to create the effects I want in the editor.
Additionally, anything on reading from the editor or a configuration file in the project would be appreciated.