procedure TForm1.FormDeactivate(Sender: TObject);
begin
        ReleaseCapture;
end;

procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
begin
        If GetCapture = 0 then
                SetCapture(Form1.Handle);
        if PtInRect(Rect(Form1.Left,Form1.Top,Form1.Left + Form1.Width,
                        Form1.Top + Form1.Height), ClientToScreen(Point(x, y))) then
                Form1.Caption := 'Мышка над формой!'
        else
                Form1.Caption := 'Мышка вне формы...';
end;