This code is taken from the tutorial written by Jörn Hameister, 
available here.
 
 This class is a generic class. It has not been adapted for JUpload. It's directly taken from Jörn Hameister tutorial
 In order to allow the unfolding of the tree one, needs a AbstractCellEditor . That's why you put a class
 MyTreeTableCellEditor to the AbstractCellEditor expanded and the TableCellEditor implemented interface. The only
 function of the class MyTreeTableCellEditor is forwarding a double-click on the tree. In the method isCellEditable is
 checked whether the first column ( column1 ) was clicked. If this is the case, a double click is on the tree forward,
 so that the ExpansionListener can respond.