Redirect keystrokes to specific component

I have a stand-alone application, which contains a JUCE on-screen Midi keyboard. It can be played by using the PC QWERTY keyboard. But at the moment I have to click on it, in order to give it the keyboard focus.

I would like the on-screen keyboard to have focus all the time, unless any "other" components needs the focus. What do I mean by any other comonent? Well, e.g. a TextEditor field. But as soon as the users presses Enter on the TextEditor field, I want the keyboard focus to go back to the on-screen keyboard.

What would be the best way to achieve that?