title: How to access component column?
body: <p>I have a grid to which I add a component column.For each row I set an icon on that column.</p>
  <p>So there might be row 1 with icon 'plus' and row two with icon 'print'.
  I need to sort the grid according to those icons like clicking on the column and bring all rows with 'print' icons first and those with 'plus' icon later,or vice versa.</p>
  <p>I can't find a way to access the rows that have a certain icon programmaticaly, while the column is not even part of the underlying data provider.It's not just icons.Take that away and replace it with a column say that stores Integers.There's no way to get that value by iterating through that grid or dataprovider.</p>
  <p>I want to do that for sorting them.Loop over the  rows that have the 'plus' icon to assign value 1 in an adjustent (artificial?) field in the underlying dataset or field/column on grid,while for those with 'print' assign the value of 0.
  I want to do that so I can sort the rows by that value.So rows with 0 come first and rows with 1 later on,because I think that's the way of doing it.</p>
  <p>I'm sorry if it does sound rather confusing,but in essence I need to find out how you can with Vaadin access a field/column of a row and change that value in the underlying dataset,<strong>or</strong> access the row on the grid and get the column value.</p>
  <p>Also what is the difference between <strong>addcomponentcolumn</strong> and <strong>addcolumn</strong>?</p>