Its very clear the documentation [1] that
Normally a widget's size is set by its parent and setFillParent must not be used. setFillParent is for convenience only when the widget's parent does not set the size of its children (such as the stage).
So, I basically should never have sceneBoard.setFillParent(true)
. Only the root table should fill its parent.
[1] https://github.com/libgdx/libgdx/wiki/Scene2d.ui#stage-setup