.controlgroup( “container” )
In jQuery Mobile 1.3.2, it was possible to add elements dynamically to data-role="controlgroup" div directly without the need to insert them into .controlgroup( "container" ).
However, things has changed in jQuery Mobile 1.4. To get best results in terms of properly formatted _controlgroup, new items should be inserted into .controlgroup( "container" ).
The previous step ensures uniform re-styling of controlgroup all elements (children) within data-role="controlgroup" and that re-styling controlgroup.
jQuery Mobile Tricks 