clicked() is emitted when the button is first pressed and then released, when the shortcut key is typed, or when click() or animateClick() is called.
triggered()This signal is emitted when an action is activated by the use
当一个左键按下释放这个过程叫做click;当一个动作被激活时。但我们点击一个动作是这连个信号都会被发出。以为我们的click激活了action。所以看起来是差不的,但我们还有其它方法比如调用 trigger()发出信号