TClrCustomControl.Anchors Property
Specifies how the control is anchored to its parent.
Use Anchors to ensure that a control maintains its current position
relative to an edge of its parent, even if the parent is resized.
When its parent is resized, the control holds its position relative
to the edges to which it is anchored.
If a control is
anchored to opposite edges of its parent, the control stretches when
its parent is resized. For example, if a control has its Anchors
property set to [akLeft, akRight], the control stretches when the
width of its parent changes.