Do you mean you want to prevent the user from clicking on things outside of the Panda window, or do you mean to disable all of the currently-active DirectGUI objects within the Panda window?
As Josh said, there’s no way to prevent the rest of the world outside of Panda from being clickable. But if you mean to disable the DirectGUI stuff, there are several approaches. Without knowing your intentions, I might recommend popping up a fade transition:
This will also have the side-effect of darkening the screen, so that the user can visually tell that the DirectGUI items have been disabled. When you want to enable it again:
This is what the DirectDialog uses when you specify fadeScreen = 0.5 to make it a modal dialog.