In Debian stable/wheezy, when there are many windows open at the same time, the windows shrink in width until there are too many windows then, I get a little arrow on the right of my last visible window button and the visible window buttons are regularly-sized.

In this installation (using Debian testing/jessie), the windows do not shrink or get that arrow that helps to keep the windows all visually accessible; instead, they just get pushed out of sight, pushing my workspace switcher out of sight as well, for example.

If more information is needed, just ask.