title: ExtJS 4 EditorGrid with Grouping: how to edit multiple rows at once
body: <p>in ExtJS 4 I have an EditorGrid with Grouping feature. I want to make it possibile to edit multiple rows at once, i.e. write a value for a field once and have it propagated to all rows in the group.</p>
  
  <p>Example: let's have a store in wich records have these fields: id, title. I want to group records by title and change all records that have title=foo with title=bar.</p>
  
  <p>Is it possibile?</p>
  
  <p>I have tried adding some custom javascript to the groupHeaderTpl but every time I click on the header the group toggle collapsing, and anyway I don't think it's a clean solution.</p>
  
  <p>Any help or hint is appreciated.</p>