Getting the Id of a double clicked item

[rsilva]

* You can set a eventFilter in the table item and check the double-click event. (subclassing the item, recommended)
* You can set a eventFilter in the main window and get the window at the mouse point. (not recommended)

When you have the QWidget of it, it's simple, you can do everything like calling objectName() or casting it to the item class to get some data.