in case he's having trouble with your terminology, technically it is a "bridge rectifier"
and you don't need a bridge rectifier in there... when you charge a battery you are applying positive voltage to the positive terminal... if you were to apply the voltage the other way around you'd drain the battery and probably destroy it. since the positive terminal is still positive, the mouse wouldn't know the difference. true, current is going through the battery in the opposite direction but only in a loop with the charger... the current supplying the mouse circuitry would just be coming from the charger at that point, and would be in the same direction as always due to the same polarity on the supplied voltage.