How to open a Popup Panel by clicking a cell in the CellTable?

I have a CellTable being displayed like shown below-

On click of the Delete button I want to open a Popup panel in the center of the screen which should contain a Flow Panel and a Button within it.
Right now for the Delete button I have the following function-

deleteColumn.setFieldUpdater(new FieldUpdater<Contact, String>() {
        public void update(int index, Contact object, String value) {           
            try {
                int removeIndex = CONTACTS.indexOf(object);
                CONTACTS.remove(removeIndex);

                table.setRowCount(CONTACTS.size(), true);
                table.setRowData(CONTACTS);

                table.redraw();

            } catch(Exception e) {
                e.printStackTrace();
            }});

I do not understand how to update my function for the same. A sample code will surely help.

How about just displaying a PopupPanel?

Something like this:

PopupPanel popup = new PopupPanel(true);
FlowPanel panel = new FlowPanel();
//add Button etc
popup.setSize("1100px","500px");
popup.clear();
popup.add(panel);
popup.show();
popup.center();

If you want to display a confirm dialog than this code is easier:

if (Window.confirm("Do you really want to delete the dataset?"))
{
     //delete code
}