Once I figured that ^ means ctrl rather than shift, then this indeed does work, but having to remember yet another key combination would be unnecessary if the menu bar were to unhide properly from the top. The issue is that one needs to put the mouse at the top pixel-row of the main display and not the top pixel-row of the highest display. When the main display is not the highest display, this is next to impossible. I would request Parallels to have the menu bar unhide in a more user-friendly way for those using multiple monitors.