Implementation:

File scripts/Navigation/DefaultNavigation/DefaultNavigation.js

Add method:

DefaultNavigation.prototype.keyPressEvent = function(event) {
    var v = undefined;

    if (event.key()===Qt.Key_Left.valueOf()) {
        v = new RVector(50, 0);
    } else if (event.key()===Qt.Key_Right.valueOf()) {
        v = new RVector(-50, 0);
    } else if (event.key()===Qt.Key_Up.valueOf()) {
        v = new RVector(0, 50);
    } else if (event.key()===Qt.Key_Down.valueOf()) {
        v = new RVector(0, -50);
    }

    if (!isNull(v)) {
        this.view.pan(v);
        event.accept();
    }
};