Editor lose focus and keyboard not functional - Ultimate 2018.3

I am paying and using IntelliJ IDEA 2018.3 Build #IU-183.4886.37 built on 17/12/2018.

I am working with it on a Macbook Pro running mojave 10.14.2.

The problem is that whenever some tool window opens due to some action (for example, pressing on Ctrl-F9 - build project), the editor lose focus and no keyboard action whatsoever is affective, the only way to get out of this, is to either Alt-Tab to another app, or click with the mouse. both workarounds are unacceptable for paid software with that price tag. 

I read forums and issues and suggestions for the last two weeks now, but none of them are either recent nor solve the problem.

I want to get a solution for this.

Thank you.

Daniel