How do I change the focus color of a pushbutton as here:
I also changed the background color of the button, and the palette, but still no change occurred.
Use stylesheets:
QPushButton:focus:pressed{ background-color: some_colour; }
QPushButton:focus{ background-color: some_other_colour; }
You can either use Qt Creator to add the styles to your button, or load them inside your code by calling setStyleSheet("...")
on your button.