Reference TControlHighlighter

  TControlHighlighter = class(TComponent)
  protected
    procedure Notification(AComponent: TComponent; Operation: TOperation); override;
    { Invoked by the animation timer to redraw the highlight }
    procedure Animate(Sender: TObject);
    procedure Loaded; override;
    { Draw the highlight, invoking OnRender if it is assigned }
    procedure Render(Surface: ISurface; Rect: TRectI); virtual;
    { Move the highlight window to the control and redraw it }
    procedure Update;
  public
    { Create a new highlighter }
    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;
  published
    { The control to highlight }
    property Control: TControl read FControl write SetControl;
    { The color of the outline }
    property Color: TColor read FColor write SetColor default clRed;
    { The distance between the control and the outline }
    property Offset: Float read FOffset write SetOffset default 4;
    { The transparency of the outline }
    property Opacity: Byte read FOpacity write SetOpacity default $7F;
    { The corner radius of the outline }
    property Radius: Float read FRadius write SetRadius default 8;
    { The width of the outline }
    property Thickness: Float read FThickness write SetThickness default 4;
    { Show or hide the highlight }
    property Visible: Boolean read FVisible write SetVisible;
    { OnRender allows custom drawing of the highlight }
    property OnRender: TDrawRectEvent read FOnRender write FOnRender;
  end;