initialize -> initializeWH
Returns an initialized FXSize instance.
Returns true if the width and height of the other size
are equal to this size’s width and height.
Returns a new size instance obtained by memberwise addition of the
other size instance with this one.
Returns a new size instance obtained by memberwise subtraction of the
other size instance from this one.
Returns a new size instance obtained by memberwise multiplication of the
width and height by value.
Returns a new size instance obtained by memberwise division of the width
and height by value.