Normally in a Grails application we have classes that are related to each other, but are located in different directories. For example a controller with several views. Or a Grails service with corresponding specifications. In IntelliJ IDEA we can use Choose Target and IDEA will show classes, files and methods that are relevant for the current file we are editing. The keybinding on my Mac OSX is Ctrl+Cmd+Up, but can be different on your computer and operating system. We can also choose the menu option Navigate | Related symbol....
In the following example we are editing the file
MessagesController. We select the action Choose Target, IntelliJ IDEA shows a popup menu with the views for this controller and the specification class:
Or if we are editing a view and select the menu option Navigate | Related symbol.... Now we can navigate to the controller, method in the controller and other views:
Written with Grails 3.0.10 and IntelliJ IDEA 15.