private void GroupButton_Click(object sender, RoutedEventArgs e)
        {
            try
            {
                if (Groups.Count == 0)
                {
                    Groups = VkApi.GetGroups(User.Uid);
                    GroupButton.ContextMenu = new System.Windows.Controls.ContextMenu();

                    foreach (var group in Groups)
                    {
                        var m = new System.Windows.Controls.MenuItem {
                            Header = @group.Name
                        };
                        var bc = new BrushConverter();
                        m.Background = (Brush)bc.ConvertFrom("#FF2D343A");
                        m.Foreground = (Brush)bc.ConvertFrom("#FFECFDFC");
                        m.Click     += m_Click3;
                        GroupButton.ContextMenu.Items.Add(m);
                    }
                }

                GroupButton.ContextMenu.IsOpen = true;
            }
            catch (NetworkInformationException)
            {
                System.Windows.Forms.MessageBox.Show(@"Ошибка интернет соединения.");
            }
        }