本例效果图:


代码文件:
--------------------------------------------------------------------------------

unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;

type
TForm1 = class(TForm)
CheckBox1: TCheckBox;
procedure CheckBox1Click(Sender: TObject);
private
procedure MyMsg(var Msg: TWMNCHitTest); message WM_NCHITTEST;
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.CheckBox1Click(Sender: TObject);
begin
SetWindowLong(Handle, GWL_STYLE, GetWindowLong(Handle, GWL_STYLE) xor WS_CAPTION);
if not CheckBox1.Checked then begin Hide; Show; end;
end;

procedure TForm1.MyMsg(var Msg: TWMNCHitTest);
begin
Inherited;
if Msg.Result = HTCLIENT then Msg.Result := HTCAPTION;
end;

end.