private void SignInButton_Click(object sender, RoutedEventArgs e)
{
var login = SignInLoginBox.Text;
var password = SignInPasswordBox.Password;
var user = _pm.CheckingPassword(login, password);
if (user is null)
{
MessageBox.Show("Incorrect login or password");
}
else
{
var appWin = new AppWindow();
Hide();
appWin.Show();
Close();
}
}