Don't miss this little sentence: "If both values are set, the first value applies to the horizontal coordinate and the second value applies to the vertical"! I can't understand why the various documentations still present vAlignement first even it's got to be written in second. When using keywords instead of numbers, vAlignement and hAlignement are togglelable ("top center" equal "center top") so why not present them in the numbers order? Adding margin/padding which have the vAlignement as first, all is done to mistake us.