title: extjs 4 How to change ordering of shown column dropdown on grid
body: <p>Using extjs 4.1.1
  I have a grid with lots of columns >20.</p>
  
  <p>Initially, most of these columns are hidden.</p>
  
  <p>If a user wants to unhide the column, they select the menu on any column, then select the "columns" choice, this expands another dropdown/dropout which shows all of the columns. Those with checkboxes next to them are shown.</p>
  
  <p>My issue is this:
  The columns in the dropdown are shown in the order in which they are defined/displayed in the grid. The order in which they are displayed in the grid has been chosen for a good reason( e.g. id as the first column). However, when a user wants to display one of the hidden columns, it is hard for them to find it in the list. This is because the list is sorted in the order the columns are defined. I want to sort the column dropdown/dropout list in alphabetical order, without effecting the order of the columns in the grid.</p>
  
  <p>How can this done?</p>