title: restrict edition to one cell in row editorGrid
body: <p>in my editorGrid i have one column  with dateField editor , when the grid is rendred i set that field to non editable : </p>
  
  <pre><code>myColModel.setEditable(colIdex,false)
  </code></pre>
  
  <p>it will be editable after the value changed in other cell in the same row</p>
  
  <pre><code>myColModel.setEditable(colIdex,true)
  </code></pre>
  
  <p>the probleme is : all the cells in the column are editables </p>
  
  <p>how can i do to make only the cell in the selected row editable</p>
  
  <p>and many thanks</p>