iTunes Screen Size Change

I usually have my MB Pro hooked up to an external monitor. I make the iTunes interface fill up the entire screen (20"). When I unplug the screen and use my computer as a laptop the iTunes interface shrinks to fit the MB Pros screen (15.4"). The only problem is that the bottom right part of the iTunes screen (the part that adjusts the size) is off the screen and thusly I can't change the size. Anyone know how to fix this?