procedure InflateRect(var R: TRect; Dx, Dy: Integer); overload;
procedure InflateRect(var FR: TFloatRect; Dx, Dy: Single); overload;
Increases (or decreases if Dx, Dy negative) the width and height of the specified rectangle:
R.Left := R.Left - Dx;
R.Right := R.Right + Dx;
R.Top := R.Top - Dy;
R.Bottom := R.Bottom + Dy;
[See also] OffsetRect