title: ExtJS Grid Column: expand column to show full content
body: <p>I created a grid having columns with fixed width.
  Due to the fixed width, some columns are not expanded enough to show full content, at least for some cells.</p>
  
  <p>Now I am looking for a way to expand this column when double clicks at its header. </p>
  
  <p>I noticed there is a function setColumnWidth() in ColumnModel, but to proceed this I have to get the maximum length of the content.</p>
  
  <p>anybody has some advice? thanks in advance!</p>