I own a 2009 13-inch MacBook Pro and a 24-inch Led Cinema Display. I have always been able to resize iTunes horizontally and vertically (both being connected to the Display and not being connected).
However, for no apparent reason, I am not able to do that anymore in both situations. I can't make the window smaller than a certain width and height (being the minimum width approximately the width resolution of the 13-inch MacBook Pro).
I've tried resizing by using option and clicking on the green button, and using option and resizing, as recommended by other users but none of these solutions have worked.
How can I allow resizing again?