title: GWT CSS DataGrid Hidden Button
body: <p>I've got a DataGrid on my GWT project. I do want add one or two buttons every grid line with hint. But when I've hover of the line they will visible, otherwise none visible. How can I do that? Like yahoo mail lines.</p>
  
  <p>Test Line1 blah blah blah
  Test Line1 blah blah blah</p>
  
  <p>if I hoover first line it can be
  Test Line1 blah bla[button1] [button2]</p>
  
  <p>Thanks,</p>