support both chart item clicked signal and rubber band in chartview at the same time

If rubber band is enabled in chartview,  clicked and pressed  signals are connected to double clicked signal.  A single click won't create the clicked signal to the chart item that is at the mouse position.   It would be nice to support both single click and rubber band as the same time.  If left mouse button is pressed  and there is no mouse movement, at the time the mouse button is released,  a clicked signal should be sent to the chart item that is at the mouse position.