control-name caption font-name foreground-colour background-colour border-type border-width left-follows top-follows right-follows bottom-follows pressed-func-name context

This property determins how the control will respond when the frame that it is on changes size and shape.

It allows the left edge of the control to be anchored to the left or right edge of the frame or to a specific vertical divider. Setting this property to "does not follow frame" causes the left edge of the control to maintain its position on the frame as its ratio of the width of the frame.