richTextBox1.Text = "sgfdjkguigheruygtb tyueghudgheghuegy uguerghuergur\n hehgiehriyi ieirhtuytiuyerth heuirtyuiy\n yetiyeti ieytiy eiytieyi";
           int last_line_pos=richTextBox1.Text.LastIndexOf('\n')+1;
           richTextBox1.SelectionStart = last_line_pos;
           richTextBox1.SelectionAlignment = HorizontalAlignment.Center;