const
 WM_MouseEnter = $B013;
 WM_MouseLeave = $B014;
type
 TfrmMain = class(TForm)
  .
  .
 Timer1: TTimer;
 procedure Timer1Timer(Sender: TObject);
 protected
 procedure WMMouseEnter(var Msg: TMessage); message WM_MouseEnter;
 end;
implementation
{$R *.dfm}
procedure TfrmMain.WMMouseEnter(var Msg: TMessage);
begin
 if(Top<0) then
 begin
 Top := 0;
 //為保證下拉窗體后呈現(xiàn)在最前面
 SetWindowPos(Handle,HWND_TOPMOST,0,0,0,0,SWP_NOMOVE or SWP_NOSIZE);
 //將窗體推到最前
 SetWindowPos(Handle,HWND_NOTOPMOST,0,0,0,0,SWP_NOMOVE or SWP_NOSIZE);
 //然后取消窗體最前
 end;
 Timer1.Enabled := True;
end;
//依賴定時器定時檢查鼠標是否還在窗體范圍內(nèi)，
//這樣此能避免因為快速移動鼠標而丟失MOUSELEAVE事件
procedure TfrmMain.Timer1Timer(Sender: TObject);
var
 rc:TRECT;
 pt:TPOINT;
begin
 GetWindowRect(self.Handle,rc); //取窗體的矩形區(qū)域
 GetCursorPos(pt); //取得當前鼠標所在位置
 if(not PtInRect(rc,pt)) then //如果鼠標不在窗體范圍內(nèi)
 begin
  if(Top = 0) then
  //如果目前窗體正吸附在屏幕上沿，則上移隱藏窗體
  begin
   Top := 0-Height+2;
  end;
  Timer1.Enabled := False; //窗體隱藏后定時器關(guān)閉
  SetWindowPos(Handle,HWND_TOPMOST,0,0,0,0,SWP_NOMOVE or SWP_NOSIZE);
  //將窗體推到最前
 end;
end;