Please see the attached images for clarification.
I extend a class "Controller" which is highlighted red because Intellij cannot find it although it is imported correctly in line 4 => hightlight_error.png
Whenever I extend the full package.classname (play.mvc.Controller) it is ok => hightlight_correct.png
Also in hightlight_error.png you can see that both a class AND a type "Controller" exist, so maybe the problem is that Intellij cannot decide which one you choose?
The code compiles and runs without errors so the compiler eventually sees no problems.