I saw the same problem just after installing 7.0b. Hover your mouse pointer over the bottom edge of the FX window when the pointer turns into the "double headed arrow" (arrows pointing up and down with parallel lines in between) pull down to extend the window.
This is mentioned in a FAQ on the SONY support site.
Tom
Try double-clicking on the title bar; that usually causes the window to properly resize to its current contents. The problem with that window is that it comes up at the size it was last set at, and that isn't always what you want.