title: Find line in which is cursor on multiline textbox
body: <p>I have to find if cursor is on first or last line in multiline textbox because of transfering focus (navigation) to other controls in GUI and have no idea how to get that.</p>
  
  <p>I can loop through textbox, get selectionstart property, count lines but I have to know if I am on first or last line with cursor.</p>
  
  <p>Any idea to achieve that?</p>