title: Check if a store (or records) have been edited?
body: <p>I have a Grid Panel, which when I leave the page, I want a check to see if any items in the store (or iterate through models/records) to check if there are any unsaved changes/additions.</p>
  
  <p>I initially tried using <code>panel.getStore().getNewRecords()</code> for new records, but it returns every record currently paged in. <code>panel.getStore().getUpdatedRecords()</code> seems to ignore records, despite lines in the grid having the small red triangle in each cell.</p>
  
  <p>So can anyone advise on the correct way to check if any new or updated records exist in a store?</p>