On some laptop keyboard the navigation keys are not present explicitly, they are emulated with the Fn key, e.g. arrow-up is Fn-8 on the numpad.
Trouble is that if I first release the Fn key, Panda3D does not generate an arrow-up-release event and for my app it is as if the key was still pressed. The only way to properly release the key is to be sure to release the modified key before the Fn key.