title: Selenium Webdriver to wait until the asyn postback update panel request is completed
body: <p>I have a table with clickable column header. On first click, the column should get sorted in ascending order and on second click column should get sorted in descending order.
  The sorting has been implemented using async postback update-panel (I am not sure how it is done, it is an aspx page).
  I would like to automate the sorting functionality using Selenium Webdriver. How can I implement the WAIT condition for the page where page doesn't get reloaded but only the table contents are reloaded. 
  <strong>waitForElementPresent</strong> wouldn't work, as no new element is displayed or hid on clicking the header.
  PS: Java implentation required.</p>