Recently I installed Windows 7 on my computer, along with a device called a Triplehead2Go, which spoofs the operating system into thinking that the computer has one monitor attached (when it really has three). When the Firefox window is relatively small on the desktop and with excess space to the right, the bookmarks toolbar opens to the right (and extends outside of the window). This creates a problem for me, as the monitor bezels get in the way of navigation. When the Firefox window is all the way to the right of the desktop, the bookmarks toolbar opens inside of the window (as there is not enough space to the right for it).

Is there any way to force this menu to stay within its boundaries?