When using QOrbitCameraController, If Qt3DWindow loses the focus when a key is pressed, key release event seems not to be handled.

Steps to reproduce:

• Open example "Qt 3D: Simple C++ Example"

• Replace

  camController->setLinearSpeed( 50.0f );

  by

camController->setLinearSpeed( 1.0f );

• Keep the key Left arrow pressed

• Right click on the title menu of the window (Or any other actions that lead to a focus lost).

• Release the key Left arrow

=> The camera moves forever, you need to press again on Left arrow to stop it.