title: DataGridView select all cells and row headers and column headers for copy
body: <p>The <code>.SelectionMode</code> of the <code>DataGridView</code> lets you select all the cells and row headers, or all the cell and column headers, but I can't figure out how to let the user select everything, including row headers and column headers at the same time.</p>
  
  <p>I would like to give users the ability to copy and paste the whole table (including the column headers) into another document as text or formatted text, like Word or an email. It works great out of the box, except you can't get the column headers too.</p>