You have been told several times what needs to be done: connect the dialog slot to the signal providing the update. The dialog you launch in response to the button press is never going to update unless you connect it to something that is going to cause it to update. It really is that simple. You will have to arrange your program so that this connection can be made, and then you have to code that connection.

The instance of the dialog you create in main() and connect to the output of your thread has nothing to do with the instance of the dialog you create in the button slot, which remains connected to nothing.