The Button accepts the following set of style attributes:
{- Colours to use when active -}
*activeForeground: black
*activeBackground: grey80
{- Idle foreground and bground. -}
*background: grey70
*foreground: black
*borderWidth: 2
*activeBorderWidth: 2
{- colour to grey out disabled button -}
*disabledForeground: grey50
{- button's shadows in idle state -}
*relief: raised
{- how much internal padding between border and label -}
*hSpace: 10
*vSpace: 20
{- disabled/enabled ? -}
*state: normal
{- Where to put the component within the button bounding box. -}
*anchor: centre