title: DataGridView capturing user row selection
body: <p>I am having trouble handling the selections in <code>DataGridView</code>.
  My grid view contains an amount column. There is a textbox on the form which should display the total amount of the selected grid view rows. Hence I need to capture events when the user selects/ deselects the gridview rows and calculate (add/ subtract) the amount accordingly. I have found two methods of doing it:</p>
  
  <ol>
  <li><p>Using the <code>RowEnter</code> and <code>RowLeave</code> events. 
  These work fine when user selects/ deselects a single row. However, when the user is selecting multiple rows at one go, the event gets fired only for the last row. Hence, from my total amount only the amount in the last row gets added/ subtracted. Thus making my result erroneous.</p></li>
  <li><p>Using the <code>RowStateChanged</code> event.
  This works for multiple rows. However, the event gets fired event if the user scrolls through the datagrid. </p></li>
  </ol>
  
  <p>Has anyone handled such a scenario. I would like to know which datagrid event I should be using, so that my code executes only when user selects/ deselects rows including multiple rows.</p>